Faster addition in string math. Now with multiplication!
#11
OMG!!  @Pete -- you won't believe what my BLEEPING BLEEP of a BLEEPING BLEEEP  BLEEEEEEP problem was!!  I've spent forever and ever and ever and ever and ever trying to track down where the glitch was in the math routines...

Are you sitting down??  Ready for this one??

CARRYOVER is a variable that *only* holds a value of either 0 or 1.  I didn't bother to define it manually, and even if I would've, I probably would've just defined it as a standard LONG...

There's a few lines in the code that look like these:

Code: (Select All)
        a = Val(Right$(a$, 18)): a$ = Left$(a$, Len(a$) - 18)
        b = Val(Right$(b$, 18)): b$ = Left$(b$, Len(b$) - 18)
        c = a + b + carryover

c = a + b + carryover <--- This is the line that's causing the glitch!!

WHY??

Because since I didn't define carryover a type, it's defaulting to a SINGLE, thus forcing the routine to do floating point math -- and in this case, we're greater than what a single can hold without losing precision!  GAAAAHH!!

Here's the fix:
Code: (Select All)
    Dim As _Unsigned _Integer64 a, b, c, carryover 'to hold our values

See the nicely defined carryover as an UINT64 now?  /Blah!




On a sidenote, I took time to dig the old BTEN$ routines out of the old version of QB64 (most folks never even realized that they were in the source code since the days of the CONST math expansions, before they got removed since nobody even realized that they were in the source code...)

Now you have multiple string math routines which you can test and compare your answers against:

Code: (Select All)
Screen _NewImage(1280, 720, 32)

a$ = "-10000000000000000000123.256"
b$ = " 60000000000000000000000.111"
Test a$, b$
a$ = " 100000000000000000000000000"
b$ = "-000000000000000000000000001.1"
Test a$, b$
a$ = "24123538548354853499345235498325489235982355952936529659265982635982398569.56466456"
b$ = "3.1"
Test a$, b$
Sub Test (a$, b$)
    Print "==========================================================================="
    Print a$
    Print b$
    Print "STEVE+:"; StringAdd(a$, b$)
    Print "BTEN +:"; BTen$(a$, "+", b$)
    Print "STEVE-:"; StringSubtract(a$, b$)
    Print "BTEN -:"; BTen$(a$, "-", b$)
    Print "==========================================================================="
    Sleep
End Sub


Function StringAdd$ (tempa$, tempb$)
    a$ = tempa$: b$ = tempb$ 'don't alter our original numbers
    Dim As _Unsigned _Integer64 a, b, c, carryover 'to hold our values

    'first fix the numbers to notmalize their lengths
    FixNumbers a$, b$
    'find the signs and strip them off
    If Left$(a$, 1) = "-" Then sa$ = "-": a$ = Mid$(a$, 2) Else sa$ = " "
    If Left$(b$, 1) = "-" Then sb$ = "-": b$ = Mid$(b$, 2) Else sb$ = " "
    'find the decimal position
    dp = InStr(a$, ".")
    If dp > 0 Then 'remove the decimal place from our numbers.  We can put it back later, in its proper position
        righta$ = Mid$(a$, dp + 1)
        rightb$ = Mid$(b$, dp + 1)
        a$ = Left$(a$, dp - 1) + righta$
        b$ = Left$(b$, dp - 1) + rightb$
    End If
    'our strings are now nothing but numbers with no signs and no decimals to deal with.  Let's start adding!
    'are we adding or really subtracting?

    If sa$ <> sb$ Then 'we're subtracting the two values if the signs aren't the same.
        Select Case a$
            Case Is < b$: s$ = sb$: Swap a$, b$ 'our sign is going to be determiined by b$
            Case Is = b$ 'if the two values are the same and are subtracting, our result is zero!
                StringAdd$ = "0" 'How easy was that?
                Exit Function
            Case Else: s$ = sa$ 'our sign is determined by a$
        End Select
        Do
            lb = Len(b$)
            a = Val(Right$(a$, 18)): a$ = Left$(a$, Len(a$) - 18)
            b = Val(Right$(b$, 18)): b$ = Left$(b$, Len(b$) - 18)
            If borrow Then b = b + 1~&& 'in case we had to borrow a digit for the last subtraction
            If a < b Then
                If lb < 18 Then a = a + 10 ^ lb Else a = a + 10 ^ 18
                borrow = -1
            Else
                borrow = 0
            End If
            c = a - b
            temp$ = _Trim$(Str$(c))
            answer$ = String$(18 - Len(temp$), "0") + temp$ + answer$
        Loop Until Len(a$) = 0
        'remove leading 0's
        Do Until Left$(answer$, 1) <> "0"
            answer$ = Mid$(answer$, 2)
        Loop
        'remember to add in the decimal place before finished
        dp = Len(righta$)
        If dp > 0 Then
            answer$ = Left$(answer$, Len(answer$) - dp) + "." + Right$(answer$, dp)
        End If
        StringAdd$ = s$ + answer$
        Exit Function
    End If

    Do
        a1$ = Right$(a$, 18)
        b1$ = Right$(b$, 18)
        a = Val(Right$(a$, 18)): a$ = Left$(a$, Len(a$) - 18)
        b = Val(Right$(b$, 18)): b$ = Left$(b$, Len(b$) - 18)
        c = a + b + carryover
        temp$ = _Trim$(Str$(c))
        If Len(temp$) > 18 Then 'see if we have an answer that is more than 18 digits
            temp$ = Right$(temp$, 18) 'keep 18 digits
            carryover = 1 'store one for carry over
        Else
            carryover = 0 'no carryover
        End If
        answer$ = String$(18 - Len(temp$), "0") + temp$ + answer$
    Loop Until Len(a$) = 0
    If carryover Then answer$ = "1" + answer$
    'remember to add in the decimal place before finished
    dp = Len(righta$)
    If dp > 0 Then
        answer$ = Left$(answer$, Len(answer$) - dp) + "." + Right$(answer$, dp)
    End If
    'remove leading 0's
    Do Until Left$(answer$, 1) <> "0"
        answer$ = Mid$(answer$, 2)
    Loop
    StringAdd$ = sa$ + answer$
End Function

Function StringSubtract$ (tempa$, tempb$)
    a$ = tempa$: b$ = tempb$
    FixNumbers a$, b$
    If Left$(b$, 1) = "-" Then b$ = Mid$(b$, 2) Else b$ = "-" + b$
    StringSubtract$ = StringAdd$(a$, b$)
End Function


Sub FixNumbers (a$, b$)
    'first remove scientific notation and spaces from both
    a$ = _Trim$(N2S$(a$)): b$ = _Trim$(N2S$(b$))
    'then find the decimal position for both and normalize the expressions
    d1 = InStr(a$, "."): d2 = InStr(b$, ".")
    If d1 <> 0 Then 'break down the left and right side of the decimal point for ease of processing  (this is a$)
        lefta$ = Left$(a$, d1 - 1)
        righta$ = Mid$(a$, d1)
    Else
        lefta$ = a$
    End If
    If d2 <> 0 Then 'break down the left and right side of the decimal point for ease of processing  (this is b$)
        leftb$ = Left$(b$, d2 - 1)
        rightb$ = Mid$(b$, d2)
    Else
        leftb$ = b$
    End If

    'normalize the right side of our expressions
    l1 = Len(righta$): l2 = Len(rightb$)
    If l1 < l2 Then
        addzero = l2 - l1
        If l1 = 0 Then righta$ = ".": addzero = addzero - 1
        righta$ = righta$ + String$(addzero, "0")
    ElseIf l1 > l2 Then
        addzero = l1 - l2
        'If l2 = 0 Then rightb$ = ".": addzero = addzero - 1
        rightb$ = rightb$ + String$(addzero, "0")
    End If



    'strip off any plus/minus signs from the two numbers.
    If Left$(lefta$, 1) = "-" Then signa$ = "-": lefta$ = Mid$(lefta$, 2)
    If Left$(leftb$, 1) = "-" Then signb$ = "-": leftb$ = Mid$(leftb$, 2)
    If Left$(lefta$, 1) = "+" Then signa$ = "": lefta$ = Mid$(lefta$, 2)
    If Left$(leftb$, 1) = "+" Then signb$ = "": leftb$ = Mid$(leftb$, 2)
    'normalize the left side of our expressions
    l1 = Len(lefta$): l2 = Len(leftb$)
    If l1 < l2 Then
        addzero = l2 - l1
        lefta$ = String$(addzero, "0") + lefta$
    ElseIf l1 > l2 Then
        addzero = l1 - l2
        leftb$ = String$(addzero, "0") + leftb$
    End If
    'and then put it all together
    a$ = signa$ + lefta$ + righta$
    b$ = signb$ + leftb$ + rightb$
End Sub





Function N2S$ (exp$) 'scientific Notation to String

    t$ = LTrim$(RTrim$(exp$))
    If Left$(t$, 1) = "-" Or Left$(t$, 1) = "N" Then sign$ = "-": t$ = Mid$(t$, 2)

    dp = InStr(t$, "D+"): dm = InStr(t$, "D-")
    ep = InStr(t$, "E+"): em = InStr(t$, "E-")
    check1 = Sgn(dp) + Sgn(dm) + Sgn(ep) + Sgn(em)
    If check1 < 1 Or check1 > 1 Then N2S = exp$: Exit Function 'If no scientic notation is found, or if we find more than 1 type, it's not SN!

    Select Case l 'l now tells us where the SN starts at.
        Case Is < dp: l = dp
        Case Is < dm: l = dm
        Case Is < ep: l = ep
        Case Is < em: l = em
    End Select

    l$ = Left$(t$, l - 1) 'The left of the SN
    r$ = Mid$(t$, l + 1): r&& = Val(r$) 'The right of the SN, turned into a workable long


    If InStr(l$, ".") Then 'Location of the decimal, if any
        If r&& > 0 Then
            r&& = r&& - Len(l$) + 2
        Else
            r&& = r&& + 1
        End If
        l$ = Left$(l$, 1) + Mid$(l$, 3)
    End If

    Select Case r&&
        Case 0 'what the heck? We solved it already?
            'l$ = l$
        Case Is < 0
            For i = 1 To -r&&
                l$ = "0" + l$
            Next
            l$ = "0." + l$
        Case Else
            For i = 1 To r&&
                l$ = l$ + "0"
            Next
    End Select

    N2S$ = sign$ + l$
End Function


Function DWD$ (exp$) 'Deal With Duplicates
    'To deal with duplicate operators in our code.
    'Such as --  becomes a +
    '++ becomes a +
    '+- becomes a -
    '-+ becomes a -
    t$ = exp$
    Do
        bad = 0
        Do
            l = InStr(t$, "++")
            If l Then t$ = Left$(t$, l - 1) + "+" + Mid$(t$, l + 2): bad = -1
        Loop Until l = 0
        Do
            l = InStr(t$, "+-")
            If l Then t$ = Left$(t$, l - 1) + "-" + Mid$(t$, l + 2): bad = -1
        Loop Until l = 0
        Do
            l = InStr(t$, "-+")
            If l Then t$ = Left$(t$, l - 1) + "-" + Mid$(t$, l + 2): bad = -1
        Loop Until l = 0
        Do
            l = InStr(t$, "--")
            If l Then t$ = Left$(t$, l - 1) + "+" + Mid$(t$, l + 2): bad = -1
        Loop Until l = 0
    Loop Until Not bad
    DWD$ = t$
End Function




Function BTen$ (InTop As String, Op As String, InBot As String)
    Rem $DYNAMIC

    InTop = LTrim$(RTrim$(InTop))
    InBot = LTrim$(RTrim$(InBot))

    l = InStr(InTop, "-")
    If l = 0 Then l = InStr(InTop, "+")
    If l = 0 Then InTop = "+" + InTop
    l = InStr(InBot, "-")
    If l = 0 Then l = InStr(InBot, "+")
    If l = 0 Then InBot = "+" + InBot

    l = InStr(InTop, ".")
    If l = 0 Then InTop = InTop + "."
    l = InStr(InBot, ".")
    If l = 0 Then InBot = InBot + "."

    If Op$ = "-" Then
        Op$ = "+"
        If Mid$(InBot, 1, 1) = "-" Then Mid$(InBot, 1, 1) = "+" Else Mid$(InBot, 1, 1) = "-"
    End If


    TDP& = Check&(10, InTop$)
    BDP& = Check&(10, InBot$)

    If TDP& < 0 Or BDP& < 0 Then Exit Function

    TSign% = Check&(11, InTop$)
    BSign% = Check&(11, InBot$)

    ' Calculate Array Size

    If Op$ = Chr$(43) Or Op$ = Chr$(45) Then
        '     "+" (Add)   OR    "-" (Subtract)
        Temp& = 9
    ElseIf Op$ = Chr$(42) Or Op$ = Chr$(50) Then
        '      "*" (Multiply) OR "2" (SQRT Multiply)
        Temp& = 7
    Else
        Exit Function
    End If

    ' LSA (Left Side of Array)
    LSA& = TDP& - 2
    TLS& = LSA& \ Temp&
    If LSA& Mod Temp& > 0 Then
        TLS& = TLS& + 1
        Do While (TLPad& + LSA&) Mod Temp& > 0
            TLPad& = TLPad& + 1
        Loop
    End If
    LSA& = BDP& - 2
    BLS& = LSA& \ Temp&
    If LSA& Mod Temp& > 0 Then
        BLS& = BLS& + 1
        Do While (BLPad& + LSA&) Mod Temp& > 0
            BLPad& = BLPad& + 1
        Loop
    End If
    If TLS& >= BLS& Then LSA& = TLS& Else LSA& = BLS&

    ' RSA (Right Side of Array)
    RSA& = Len(InTop$) - TDP&
    TRS& = RSA& \ Temp&
    If RSA& Mod Temp& > 0 Then
        TRS& = TRS& + 1
        Do While (TRPad& + RSA&) Mod Temp& > 0
            TRPad& = TRPad& + 1
        Loop
    End If
    RSA& = Len(InBot$) - BDP&
    BRS& = RSA& \ Temp&
    If RSA& Mod Temp& > 0 Then
        BRS& = BRS& + 1
        Do While (BRPad& + RSA&) Mod Temp& > 0
            BRPad& = BRPad& + 1
        Loop
    End If
    If TRS& >= BRS& Then RSA& = TRS& Else RSA& = BRS&



    If Op$ = Chr$(43) Or Op$ = Chr$(45) Then
        '     "+" (Add)   OR    "-" (Subtract)

        Dim Result(1 To (LSA& + RSA&)) As Long

        If (Op$ = Chr$(43) And TSign% = BSign%) Or (Op$ = Chr$(45) And TSign% <> BSign%) Then
            ' Add Absolute Values and Return Top Sign

            ' Left Side
            For I& = 1 To LSA&
                ' Top
                If I& <= (LSA& - TLS&) Then
                    ''' Result(I&) = Result(I&) + 0
                ElseIf I& = (1 + LSA& - TLS&) Then
                    Result(I&) = Val(Mid$(InTop$, 2, (9 - TLPad&)))
                    TDP& = 11 - TLPad&
                Else
                    Result(I&) = Val(Mid$(InTop$, TDP&, 9))
                    TDP& = TDP& + 9
                End If
                ' Bottom
                If I& <= (LSA& - BLS&) Then
                    ''' Result(I&) = Result(I&) + 0
                ElseIf I& = (1 + LSA& - BLS&) Then
                    Result(I&) = Result(I&) + Val(Mid$(InBot$, 2, (9 - BLPad&)))
                    BDP& = 11 - BLPad&
                Else
                    Result(I&) = Result(I&) + Val(Mid$(InBot$, BDP&, 9))
                    BDP& = BDP& + 9
                End If
            Next I&

            ' Right Side
            TDP& = TDP& + 1: BDP& = BDP& + 1
            For I& = (LSA& + 1) To (LSA& + RSA&)
                ' Top
                If I& > (LSA& + TRS&) Then
                    ''' Result(I&) = Result(I&) + 0
                ElseIf I& = (LSA& + TRS&) Then
                    Result(I&) = (10 ^ TRPad&) * Val(Right$(InTop$, (9 - TRPad&)))
                Else
                    Result(I&) = Val(Mid$(InTop$, TDP&, 9))
                    TDP& = TDP& + 9
                End If
                ' Bottom
                If I& > (LSA& + BRS&) Then
                    ''' Result(I&) = Result(I&) + 0
                ElseIf I& = (LSA& + BRS&) Then
                    Result(I&) = Result(I&) + (10 ^ BRPad&) * Val(Right$(InBot$, (9 - BRPad&)))
                Else
                    Result(I&) = Result(I&) + Val(Mid$(InBot$, BDP&, 9))
                    BDP& = BDP& + 9
                End If
            Next I&

            ' Carry
            For I& = (LSA& + RSA&) To 2 Step -1
                If Result(I&) >= 1000000000 Then
                    Result(I& - 1) = Result(I& - 1) + 1
                    Result(I&) = Result(I&) - 1000000000
                End If
            Next I&

            ' Return Sign
            If TSign% = 1 Then RetStr$ = Chr$(43) Else RetStr$ = Chr$(45)

        Else
            ' Compare Absolute Values

            If TDP& > BDP& Then
                Compare& = 1
            ElseIf TDP& < BDP& Then
                Compare& = -1
            Else
                If Len(InTop$) > Len(InBot$) Then Compare& = Len(InBot$) Else Compare& = Len(InTop$)
                For I& = 2 To Compare&
                    If Val(Mid$(InTop$, I&, 1)) > Val(Mid$(InBot$, I&, 1)) Then
                        Compare& = 1
                        Exit For
                    ElseIf Val(Mid$(InTop$, I&, 1)) < Val(Mid$(InBot$, I&, 1)) Then
                        Compare& = -1
                        Exit For
                    End If
                Next I&
                If Compare& > 1 Then
                    If Len(InTop$) > Len(InBot$) Then
                        Compare& = 1
                    ElseIf Len(InTop$) < Len(InBot$) Then
                        Compare& = -1
                    Else
                        Compare& = 0
                    End If
                End If
            End If

            ' Conditional Subtraction

            If Compare& = 1 Then
                ' Subtract Bottom from Top and Return Top Sign

                ' Top
                Result(1) = Val(Mid$(InTop$, 2, (9 - TLPad&)))
                TDP& = 11 - TLPad&
                For I& = 2 To LSA&
                    Result(I&) = Val(Mid$(InTop$, TDP&, 9))
                    TDP& = TDP& + 9
                Next I&
                TDP& = TDP& + 1
                For I& = (LSA& + 1) To (LSA& + TRS& - 1)
                    Result(I&) = Val(Mid$(InTop$, TDP&, 9))
                    TDP& = TDP& + 9
                Next I&
                Result(LSA& + TRS&) = 10& ^ TRPad& * Val(Right$(InTop$, (9 - TRPad&)))

                ' Bottom
                BDP& = (Len(InBot$) - 17) + BRPad&
                For I& = (LSA& + BRS&) To (1 + LSA& - BLS&) Step -1
                    If I& = LSA& Then BDP& = BDP& - 1
                    If I& = (LSA& + BRS&) Then
                        Temp& = (10& ^ BRPad&) * Val(Right$(InBot$, (9 - BRPad&)))
                    ElseIf I& = (1 + LSA& - BLS&) Then
                        Temp& = Val(Mid$(InBot$, 2, (9 - BLPad&)))
                    Else
                        Temp& = Val(Mid$(InBot$, BDP&, 9))
                        BDP& = BDP& - 9
                    End If
                    If Result(I&) < Temp& Then
                        ' Borrow
                        For J& = (I& - 1) To 1 Step -1
                            If Result(J&) = 0 Then
                                Result(J&) = 999999999
                            Else
                                Result(J&) = Result(J&) - 1
                                Exit For
                            End If
                        Next J&
                        Result(I&) = Result(I&) + 1000000000
                    End If
                    Result(I&) = Result(I&) - Temp&
                Next I&

                ' Return Sign
                If TSign% = 1 Then RetStr$ = Chr$(43) Else RetStr$ = Chr$(45)

            ElseIf Compare& = -1 Then
                ' Subtract Top from Bottom and Return Bottom Sign

                ' Bottom
                Result(1) = Val(Mid$(InBot$, 2, (9 - BLPad&)))
                BDP& = 11 - BLPad&
                For I& = 2 To LSA&
                    Result(I&) = Val(Mid$(InBot$, BDP&, 9))
                    BDP& = BDP& + 9
                Next I&
                BDP& = BDP& + 1
                For I& = (LSA& + 1) To (LSA& + BRS& - 1)
                    Result(I&) = Val(Mid$(InBot$, BDP&, 9))
                    BDP& = BDP& + 9
                Next I&
                Result(LSA& + BRS&) = 10& ^ BRPad& * Val(Right$(InBot$, (9 - BRPad&)))

                ' Top
                TDP& = (Len(InTop$) - 17) + TRPad&
                For I& = (LSA& + TRS&) To (1 + LSA& - TLS&) Step -1
                    If I& = LSA& Then TDP& = TDP& - 1
                    If I& = (LSA& + TRS&) Then
                        Temp& = (10& ^ TRPad&) * Val(Right$(InTop$, (9 - TRPad&)))
                    ElseIf I& = (1 + LSA& - TLS&) Then
                        Temp& = Val(Mid$(InTop$, 2, (9 - TLPad&)))
                    Else
                        Temp& = Val(Mid$(InTop$, TDP&, 9))
                        TDP& = TDP& - 9
                    End If
                    If Result(I&) < Temp& Then
                        ' Borrow
                        For J& = (I& - 1) To 1 Step -1
                            If Result(J&) = 0 Then
                                Result(J&) = 999999999
                            Else
                                Result(J&) = Result(J&) - 1
                                Exit For
                            End If
                        Next J&
                        Result(I&) = Result(I&) + 1000000000
                    End If
                    Result(I&) = Result(I&) - Temp&
                Next I&

                ' Build Return Sign
                If BSign% = 1 Then RetStr$ = Chr$(43) Else RetStr$ = Chr$(45)

            Else
                ' Result will always be 0

                LSA& = 1: RSA& = 1
                RetStr$ = Chr$(43)

            End If
        End If

        ' Generate Return String
        RetStr$ = RetStr$ + LTrim$(Str$(Result(1)))
        For I& = 2 To LSA&
            RetStr$ = RetStr$ + Right$(String$(8, 48) + LTrim$(Str$(Result(I&))), 9)
        Next I&
        RetStr$ = RetStr$ + Chr$(46)
        For I& = (LSA& + 1) To (LSA& + RSA&)
            RetStr$ = RetStr$ + Right$(String$(8, 48) + LTrim$(Str$(Result(I&))), 9)
        Next I&

        Erase Result

    ElseIf Op$ = Chr$(42) Then
        ' * (Multiply)

        Dim TArray(1 To (LSA& + RSA&)) As Long
        Dim BArray(1 To (LSA& + RSA&)) As Long
        Dim ResDBL(0 To (LSA& + RSA&)) As Double

        ' Push String Data Into Array
        For I& = 1 To LSA&
            If I& <= (LSA& - TLS&) Then
                ''' TArray(I&) = TArray(I&) + 0
            ElseIf I& = (1 + LSA& - TLS&) Then
                TArray(I&) = Val(Mid$(InTop$, 2, (7 - TLPad&)))
                TDP& = 9 - TLPad&
            Else
                TArray(I&) = Val(Mid$(InTop$, TDP&, 7))
                TDP& = TDP& + 7
            End If
            If I& <= (LSA& - BLS&) Then
                ''' BArray(I&) = BArray(I&) + 0
            ElseIf I& = (1 + LSA& - BLS&) Then
                BArray(I&) = Val(Mid$(InBot$, 2, (7 - BLPad&)))
                BDP& = 9 - BLPad&
            Else
                BArray(I&) = Val(Mid$(InBot$, BDP&, 7))
                BDP& = BDP& + 7
            End If
        Next I&
        TDP& = TDP& + 1: BDP& = BDP& + 1
        For I& = (LSA& + 1) To (LSA& + RSA&)
            If I& > (LSA& + TRS&) Then
                ''' TArray(I&) = TArray(I&) + 0
            ElseIf I& = (LSA& + TRS&) Then
                TArray(I&) = 10 ^ TRPad& * Val(Right$(InTop$, (7 - TRPad&)))
            Else
                TArray(I&) = Val(Mid$(InTop$, TDP&, 7))
                TDP& = TDP& + 7
            End If
            If I& > (LSA& + BRS&) Then
                ''' BArray(I&) = BArray(I&) + 0
            ElseIf I& = (LSA& + BRS&) Then
                BArray(I&) = 10 ^ BRPad& * Val(Right$(InBot$, (7 - BRPad&)))
            Else
                BArray(I&) = Val(Mid$(InBot$, BDP&, 7))
                BDP& = BDP& + 7
            End If
        Next I&

        ' Multiply from Arrays to Array
        For I& = (LSA& + TRS&) To (1 + LSA& - TLS&) Step -1
            For J& = (LSA& + BRS&) To (1 + LSA& - BLS&) Step -1
                Temp# = 1# * TArray(I&) * BArray(J&)
                If (I& + J&) Mod 2 = 0 Then
                    TL& = Int(Temp# / 10000000)
                    TR& = Temp# - 10000000# * TL&
                    ResDBL(((I& + J&) \ 2) - 1) = ResDBL(((I& + J&) \ 2) - 1) + TL&
                    ResDBL((I& + J&) \ 2) = ResDBL((I& + J&) \ 2) + 10000000# * TR&
                Else
                    ResDBL((I& + J&) \ 2) = ResDBL((I& + J&) \ 2) + Temp#
                End If
                If ResDBL((I& + J&) \ 2) >= 100000000000000# Then
                    Temp# = ResDBL((I& + J&) \ 2)
                    TL& = Int(Temp# / 100000000000000#)
                    ResDBL(((I& + J&) \ 2) - 1) = ResDBL(((I& + J&) \ 2) - 1) + TL&
                    ResDBL((I& + J&) \ 2) = Temp# - 100000000000000# * TL&
                End If
            Next J&
        Next I&

        Erase TArray, BArray

        ' Generate Return String
        If (TSign% * BSign%) = 1 Then RetStr$ = Chr$(43) Else RetStr$ = Chr$(45)
        RetStr$ = RetStr$ + LTrim$(Str$(ResDBL(0)))
        For I& = 1 To (LSA&)
            RetStr$ = RetStr$ + Right$(String$(13, 48) + LTrim$(Str$(ResDBL(I&))), 14)
        Next I&
        RetStr$ = Left$(RetStr$, Len(RetStr$) - 7) + Chr$(46) + Right$(RetStr$, 7)
        For I& = (LSA& + 1) To (LSA& + RSA&)
            RetStr$ = RetStr$ + Right$(String$(13, 48) + LTrim$(Str$(ResDBL(I&))), 14)
        Next I&

        Erase ResDBL

    ElseIf Op$ = Chr$(50) Then
        ' 2 (SQRT Multiply)

        Dim IArray(1 To (LSA& + RSA&)) As Long
        Dim ResDBL(0 To (LSA& + RSA&)) As Double

        ' Push String Data Into Array
        For I& = 1 To LSA&
            If I& <= (LSA& - TLS&) Then
                ''' IArray(I&) = IArray(I&) + 0
            ElseIf I& = (1 + LSA& - TLS&) Then
                IArray(I&) = Val(Mid$(InTop$, 2, (7 - TLPad&)))
                TDP& = 9 - TLPad&
            Else
                IArray(I&) = Val(Mid$(InTop$, TDP&, 7))
                TDP& = TDP& + 7
            End If
        Next I&
        TDP& = TDP& + 1
        For I& = (LSA& + 1) To (LSA& + RSA&)
            If I& > (LSA& + TRS&) Then
                ''' IArray(I&) = IArray(I&) + 0
            ElseIf I& = (LSA& + TRS&) Then
                IArray(I&) = 10 ^ TRPad& * Val(Right$(InTop$, (7 - TRPad&)))
            Else
                IArray(I&) = Val(Mid$(InTop$, TDP&, 7))
                TDP& = TDP& + 7
            End If
        Next I&

        ' SQRT Multiply from Array to Array
        For I& = (LSA& + TRS&) To 1 Step -1
            For J& = I& To 1 Step -1
                Temp# = 1# * IArray(I&) * IArray(J&)
                If I& <> J& Then Temp# = Temp# * 2
                If (I& + J&) Mod 2 = 0 Then
                    TL& = Int(Temp# / 10000000)
                    TR& = Temp# - 10000000# * TL&
                    ResDBL(((I& + J&) \ 2) - 1) = ResDBL(((I& + J&) \ 2) - 1) + TL&
                    ResDBL((I& + J&) \ 2) = ResDBL((I& + J&) \ 2) + 10000000# * TR&
                Else
                    ResDBL((I& + J&) \ 2) = ResDBL((I& + J&) \ 2) + Temp#
                End If
                If ResDBL((I& + J&) \ 2) >= 100000000000000# Then
                    Temp# = ResDBL((I& + J&) \ 2)
                    TL& = Int(Temp# / 100000000000000#)
                    ResDBL(((I& + J&) \ 2) - 1) = ResDBL(((I& + J&) \ 2) - 1) + TL&
                    ResDBL((I& + J&) \ 2) = Temp# - 100000000000000# * TL&
                End If
            Next J&
        Next I&

        Erase IArray

        ' Generate Return String
        If (TSign% * BSign%) = 1 Then RetStr$ = Chr$(43) Else RetStr$ = Chr$(45)
        RetStr$ = RetStr$ + LTrim$(Str$(ResDBL(0)))
        For I& = 1 To (LSA&)
            RetStr$ = RetStr$ + Right$(String$(13, 48) + LTrim$(Str$(ResDBL(I&))), 14)
        Next I&
        RetStr$ = Left$(RetStr$, Len(RetStr$) - 7) + Chr$(46) + Right$(RetStr$, 7)
        ' Don't usually want the full right side for this, just enough to check the
        ' actual result against the expected result, which is probably an integer.
        ' Uncomment the three lines below when trying to find an oddball square root.
        'FOR I& = (LSA& + 1) TO (LSA& + RSA&)
        '    RetStr$ = RetStr$ + RIGHT$(STRING$(13, 48) + LTRIM$(STR$(ResDBL(I&))), 14)
        'NEXT I&

        Erase ResDBL

    End If

    ' Trim Leading and Trailing Zeroes
    Do While Mid$(RetStr$, 2, 1) = Chr$(48) And Mid$(RetStr$, 3, 1) <> Chr$(46)
        RetStr$ = Left$(RetStr$, 1) + Right$(RetStr$, Len(RetStr$) - 2)
    Loop
    Do While Right$(RetStr$, 1) = Chr$(48) And Right$(RetStr$, 2) <> Chr$(46) + Chr$(48)
        RetStr$ = Left$(RetStr$, Len(RetStr$) - 1)
    Loop


    If Mid$(RetStr$, 1, 1) = "+" Then Mid$(RetStr$, 1, 1) = " "
    Do
        r$ = Right$(RetStr$, 1)
        If r$ = "0" Then RetStr$ = Left$(RetStr$, Len(RetStr$) - 1)
    Loop Until r$ <> "0"

    r$ = Right$(RetStr$, 1)
    If r$ = "." Then RetStr$ = Left$(RetStr$, Len(RetStr$) - 1)

    BTen$ = RetStr$
End Function
Rem $STATIC
' ---------------------------------------------------------------------------
' FUNCTION Check& (Op&, InString$)                Multi-Purpose String Tester
' ---------------------------------------------------------------------------
'
' *   Op&   = Type of string to expect and/or operation to perform
'
'   { 00A } = (10) Test Base-10-Format String  ( *!* ALTERS InString$ *!* )
'   { 00B } = (11) Read Sign ("+", "-", or CHR$(241))
'
'   Unlisted values are not used and will return [ Check& = 0 - Op& ].
'   Different Op& values produce various return values.
'   Refer to the in-code comments for details.
'
' ---------------------------------------------------------------------------
' FUNCTION Check& (Op&, InString$)                Multi-Purpose String Tester
' ---------------------------------------------------------------------------
Function Check& (Op As Long, InString As String)
    Rem $DYNAMIC

    RetVal& = Len(InString$)

    Select Case Op&

        Case 10
            ' {00A} Test String for Base-10-Format ( *!* ALTERS InString$ *!* )
            ' Returns:
            ' {& > 0} = DP offset; {& < 0} = FAILED at negative offset
            '
            ' After testing passes, the string is trimmed
            ' of nonessential leading and trailing zeroes.

            If RetVal& = 0 Then
                RetVal& = -1
            Else
                Select Case Asc(Left$(InString$, 1))
                    Case 43, 45 ' "+", "-"
                        For I& = 2 To RetVal&
                            Select Case Asc(Mid$(InString$, I&, 1))
                                Case 46 ' "."
                                    If DPC% > 0 Then
                                        RetVal& = 0 - I&
                                        Exit For
                                    Else
                                        DPC% = DPC% + 1
                                        RetVal& = I&
                                    End If
                                Case 48 To 57
                                    ' keep going
                                Case Else
                                    RetVal& = 0 - I&
                                    Exit For
                            End Select
                        Next I&
                    Case Else
                        RetVal& = -1
                End Select
                If DPC% = 0 And RetVal& > 0 Then
                    RetVal& = 0 - RetVal&
                ElseIf RetVal& = 2 Then
                    InString$ = Left$(InString$, 1) + Chr$(48) + Right$(InString$, Len(InString$) - 1)
                    RetVal& = RetVal& + 1
                End If
                If RetVal& = Len(InString$) Then InString$ = InString$ + Chr$(48)
                Do While Asc(Right$(InString$, 1)) = 48 And RetVal& < (Len(InString$) - 1)
                    InString$ = Left$(InString$, Len(InString$) - 1)
                Loop
                Do While Asc(Mid$(InString$, 2, 1)) = 48 And RetVal& > 3
                    InString$ = Left$(InString$, 1) + Right$(InString$, Len(InString$) - 2)
                    RetVal& = RetVal& - 1
                Loop
            End If


        Case 11
            ' {00B} Read Sign ("+", "-", or CHR$(241))
            ' Returns:
            ' Explicit: +1 = Positive; -1 = Negative; 0 = Unsigned;
            ' Implied: +64 = Positive; -64 = NULL String

            If RetVal& = 0 Then RetVal& = -64
            For I& = 1 To RetVal&
                Select Case Asc(Mid$(InString$, I&, 1))
                    Case 32
                        RetVal& = 64
                        ' keep going
                    Case 43
                        RetVal& = 1
                        Exit For
                    Case 45
                        RetVal& = -1
                        Exit For
                    Case 241
                        RetVal& = 0
                        Exit For
                    Case Else
                        RetVal& = 64
                        Exit For
                End Select
            Next I&


        Case Else

            RetVal& = 0 - Op&

    End Select

    Check& = RetVal&
End Function

And for what it's worth, BTEN$ does "+", "-", "*", and "SQRT", IIRC.  Wink
Reply
#12
Hi Steve Smile
your bten$ routines are fast considering that it's string based, how would you call the Sqrt function?
Reply
#13
(08-19-2022, 09:54 PM)Jack Wrote: Hi Steve Smile
your bten$ routines are fast considering that it's string based, how would you call the Sqrt function?

BTEN wasn't mine; it was something someone else worked up ages ago.  Dark...something...   Darkstar, perhaps?  You might remember him from the old .net forums of Galleons (not .org of Fellippes).  He was the guy perpetually working on a space game with the idea of a 3d array storing every point in the universe.  I was never certain exactly how you'd store such vast amounts of data in an array, but he claimed to have it all sorted out.  Unfortunately, he disappeared back when the forums collapsed the first time at .net.

From what I recall, SQRT worked off the first parameter only, with the last parameter being ignored.

result$ = BTEN$("2", "SQRT", "ignored") -- IIRC.

I don't recall how you set a limit to how many digits to generate.  I remember Dark once posted several thousand digits to the SQRT of 2, or something once, where he had it output the answer to a file as it calculated the result.  You'll just have to skim the code and play with it, I'm afraid.  I didn't write BTEN, and haven't used it for years.  Last version of QB64.bas with it inside was back around v1.1, IIRC, and that was when Galleon was still doing releases!  Wink
Reply
#14
@Jack I spent a little time digging into the source for BTEN$ -- apparently this version doesn't actually calculate SQRT for us. Instead, it SQUARES a number for us. (x ^ 2)

I definitely remember there being a string routine which did square roots, but from what I remember of the layout of the code, it wasn't structured anything like this. What Dark had created for his square root calculator was a simple process that took 2 numbers and multiplied them together to aim for the target value and expanded one digit at a time.

For example to calculate the square root of 2, it'd first see what QB64 would give it as a seed.
Seed = SQR(2) ... which QB64 tells us is 1.414213562373095

Then it'd multiple that value by itself to see if it had a perfect match.
If not, it'd then multiple that value + "5" by itself. 1.4142135623730955 <-- see the added 5?
That value would then multiply by itself.
If the result was > the target, ir changed 5 to 2 and tried again. 1.4142135623730952 <-- 2 at the end
If the result was < the target, it changed 5 to 8 and tried again. 1.4142135623730958 <-- 8 at the end

And it basically continued this process until it narrowed the range to being between to digits. 2 is too small, 3 is too large -- the target value is 2!

And then it repeated that same multiplication process once again to get the next digit. 1.4142135623730952 + "5"

And that's how Dark's SQRT code worked, from what I remember of it, wherever the heck it went!



As for what's in the BTEN, you can use it via a simple call like so:

result$ = BTEN$(num$, "2", "") <-- and this will square the number for you.

Why he wrote a whole operator to handle such a thing, I don't know, and there's no way to ask him now that I know of. Seems to me that it'd be just as easy to do a simple: result$ = BTEN$(num$, "*", num$)

I'll dig around on the hard drives some later and see if I can find his actual SQRT calculator. I remember well how it works, but for whatever reason, it's not a part of the BTEN string routine which he shared and put into QB64 back in the day.
Reply
#15
@SMcNeill

Glad you found it.

I added (excuse the pun) a chunk multiple routine. It may be buggy, as I haven't tested it all that well. I had to vary a bit from the structure I used for addition/subtraction, but not too much. I might go back and tweak the two a bit latter. Anyway, these changes are proving to be a faster model than my old string routines from a few years ago.

The Holly grail would be a way to do chunk division, but that's one hell of a rabbit hole to go down.

Here's the updated code for +, - , and now *

Code: (Select All)
betatest% = 0
DIM AS _INTEGER64 a, b, c, aa, bb, cc, s, ss
WIDTH 160, 42
_SCREENMOVE 0, 0

DO
    LINE INPUT "Number: "; a$
    IF a$ = "" THEN EXIT DO ' Quit.
    LINE INPUT "+ - * : "; op$
    LINE INPUT "Number: "; b$

    a1$ = a$: b1$ = b$

    SELECT CASE op$
        CASE "*"
            z$ = "": sign$ = "": mult&& = 0: h&& = 0: i&& = 0: j&& = 0: c = 0: decimal% = 0
            zz$ = "": ii&& = 0: jj&& = 0
            s = 8: ss = 18

            IF INSTR(a$, "-") <> 0 OR INSTR(b$, "-") <> 0 THEN
                IF INSTR(a$, "-") <> 0 AND INSTR(b$, "-") <> 0 THEN
                    a$ = MID$(a$, 2): b$ = MID$(b$, 2)
                ELSE
                    IF INSTR(a$, "-") <> 0 THEN a$ = MID$(a$, 2) ELSE b$ = MID$(b$, 2)
                    sign$ = "-"
                END IF
            END IF

            IF INSTR(a$, ".") <> 0 OR INSTR(b$, ".") <> 0 THEN
                decimal% = -1
                IF INSTR(a$, ".") <> 0 THEN
                    dec_a&& = LEN(MID$(a$, INSTR(a$, ".") + 1))
                    a$ = MID$(a$, 1, INSTR(a$, ".") - 1) + MID$(a$, INSTR(a$, ".") + 1)
                END IF
                IF INSTR(b$, ".") <> 0 THEN
                    dec_b&& = LEN(MID$(b$, INSTR(b$, ".") + 1))
                    b$ = MID$(b$, 1, INSTR(b$, ".") - 1) + MID$(b$, INSTR(b$, ".") + 1)
                END IF
            END IF

            IF LEN(a$) < LEN(b$) THEN SWAP a$, b$

            DO
                h&& = h&& + s: i&& = 0
                x2$ = MID$(b$, LEN(b$) - h&& + 1, s)
                WHILE -1
                    i&& = i&& + s
                    x1$ = MID$(a$, LEN(a$) - i&& + 1, s)
                    a = VAL(sign_a$ + x1$) * VAL(sign_b$ + x2$) + c
                    IF betatest% THEN PRINT "x1$ = "; x1$;: LOCATE , 20: PRINT "x2$ = "; x2$;: LOCATE , 35: PRINT VAL(x1$) * VAL(x2$) + c;: LOCATE , 55: PRINT "c = "; c;: LOCATE , 75: PRINT "val = "; a,
                    c = 0
                    tmp$ = LTRIM$(STR$(a))
                    IF LEN(tmp$) > s THEN c = VAL(MID$(tmp$, 1, LEN(tmp$) - s)): tmp$ = MID$(tmp$, LEN(tmp$) - s + 1)
                    z$ = tmp$ + z$
                    IF betatest% THEN LOCATE , 100: PRINT a;: LOCATE , 120: PRINT z$
                    IF i&& >= LEN(a$) AND c = 0 THEN EXIT WHILE
                WEND

                jj&& = jj&& + 1

                IF jj&& > 1 THEN
                    ii&& = 0: cc = 0
                    aa$ = holdaa$
                    bb$ = z$ + STRING$((jj&& - 1) * s, "0")
                    IF betatest% THEN PRINT "aa$ "; aa$; " + bb$ "; z$;: COLOR 14, 0: PRINT STRING$(jj&& - 1, "0"); " = ";: COLOR 7, 0: SLEEP
                    DO
                        ii&& = ii&& + ss
                        xx1$ = MID$(aa$, LEN(aa$) - ii&& + 1, ss)
                        xx2$ = MID$(bb$, LEN(bb$) - ii&& + 1, ss)
                        aa = VAL(xx1$) + VAL(xx2$) + cc
                        IF xx1$ + xx2$ = "" AND cc = 0 THEN EXIT DO ' Prevents leading zeros.
                        cc = 0
                        IF aa > VAL(STRING$(ss, "9")) THEN aa = aa - 10 ^ ss: cc = 1
                        tmp$ = LTRIM$(STR$(aa))
                        zz$ = STRING$(ss - LEN(tmp$), "0") + tmp$ + zz$
                        REM PRINT xx1$;: LOCATE , 15: PRINT xx2$;: LOCATE , 30: PRINT VAL(xx1$) + VAL(xx2$);: LOCATE , 45: PRINT cc;: LOCATE , 60: PRINT aa, "z$ = "; zz$: SLEEP
                    LOOP

                    DO WHILE LEFT$(zz$, 1) = "0"
                        IF LEFT$(zz$, 1) = "0" THEN zz$ = MID$(zz$, 2)
                    LOOP
                    IF zz$ = "" THEN zz$ = "0"

                    holdaa$ = zz$
                    IF betatest% THEN COLOR 2, 0: PRINT holdaa$: COLOR 7, 0
                ELSE
                    holdaa$ = z$ + STRING$(jj&& - 1, "0")
                END IF

                z$ = "": zz$ = ""
            LOOP UNTIL h&& >= LEN(b$)

            z$ = holdaa$

            IF decimal% THEN
                DO UNTIL LEN(z$) >= dec_a&& + dec_b&&
                    z$ = "0" + z$
                LOOP

                z$ = MID$(z$, 0, LEN(z$) - (dec_a&& + dec_b&& - 1)) + "." + MID$(z$, LEN(z$) - (dec_a&& + dec_b&&) + 1)

                DO UNTIL RIGHT$(z$, 1) <> "0" AND RIGHT$(z$, 1) <> "."
                    z$ = MID$(z$, 1, LEN(z$) - 1)
                LOOP
            END IF

            IF z$ = "" OR z$ = "0" THEN z$ = "0": ELSE z$ = sign$ + z$

            PRINT " " + LTRIM$(STR$(VAL(a1$) * VAL(b1$))), "QB64 VAL()."
            PRINT " "; z$, "String Math."
            PRINT

            decimal% = 0: sign$ = ""

        CASE "+", "-"
            s = 18

            IF op$ = "-" THEN
                IF LEFT$(b$, 1) = "-" THEN b$ = MID$(b$, 2) ELSE b$ = "-" + b$
            END IF

            IF INSTR(a$, ".") <> 0 OR INSTR(b$, ".") <> 0 THEN
                decimal% = -1
                IF INSTR(a$, ".") <> 0 THEN
                    dec_a&& = LEN(MID$(a$, INSTR(a$, ".") + 1))
                    a$ = MID$(a$, 1, INSTR(a$, ".") - 1) + MID$(a$, INSTR(a$, ".") + 1)
                END IF
                IF INSTR(b$, ".") <> 0 THEN
                    dec_b&& = LEN(MID$(b$, INSTR(b$, ".") + 1))
                    b$ = MID$(b$, 1, INSTR(b$, ".") - 1) + MID$(b$, INSTR(b$, ".") + 1)
                END IF
                ' Line up decimal places by inserting trailing zeros.
                IF dec_b&& > dec_a&& THEN
                    j&& = dec_b&&
                    a$ = a$ + STRING$(dec_b&& - dec_a&&, "0")
                ELSE
                    j&& = dec_a&&
                    b$ = b$ + STRING$(dec_a&& - dec_b&&, "0")
                END IF
            END IF

            IF LEFT$(a$, 1) = "-" OR LEFT$(b$, 1) = "-" THEN
                IF LEFT$(a$, 1) = "-" AND LEFT$(b$, 1) = "-" THEN
                    sign$ = "--": a$ = MID$(a$, 2): b$ = MID$(b$, 2)
                ELSE
                    IF LEFT$(a$, 1) = "-" THEN a$ = MID$(a$, 2): sign_a$ = "-"
                    IF LEFT$(b$, 1) = "-" THEN b$ = MID$(b$, 2): sign_b$ = "-"

                    string_compare LTRIM$(STR$(ABS(VAL(a1$)))), LTRIM$(STR$(ABS(VAL(b1$)))), gl%

                    IF gl% < 0 THEN
                        IF LEN(sign_b$) THEN sign$ = "-": SWAP a$, b$
                    ELSE
                        IF LEN(sign_a$) THEN sign$ = "-": SWAP sign_a$, sign_b$
                    END IF
                END IF
            END IF

            z$ = ""
            DO
                i&& = i&& + s
                x1$ = MID$(a$, LEN(a$) - i&& + 1, s)
                x2$ = MID$(b$, LEN(b$) - i&& + 1, s)
                a = VAL(sign_a$ + x1$) + VAL(sign_b$ + x2$) + c
                IF x1$ + x2$ = "" AND c = 0 THEN EXIT DO ' Prevents leading zeros.
                c = 0
                IF a > VAL(STRING$(s, "9")) THEN a = a - 10 ^ s: c = 1
                IF a < 0 THEN a = a + 10 ^ s: c = -1
                z$ = LTRIM$(STR$(a)) + z$
                REM PRINT x1$;: LOCATE , 15: PRINT x2$;: LOCATE , 30: PRINT VAL(x1$) - VAL(x2$);: LOCATE , 45: PRINT c;: LOCATE , 60: PRINT a, z$: SLEEP
            LOOP

            IF decimal% THEN
                z$ = MID$(z$, 1, LEN(z$) - j&&) + "." + MID$(z$, LEN(z$) - j&& + 1)
            END IF

            ' Remove any leading zeros.
            DO
                IF LEFT$(z$, 1) = "0" THEN z$ = MID$(z$, 2) ELSE EXIT DO
            LOOP

            IF z$ = "" OR z$ = "0" THEN z$ = "0" ELSE z$ = LEFT$(sign$, 1) + z$

            IF op$ = "+" THEN PRINT " " + LTRIM$(STR$(VAL(a1$) + VAL(b1$))), "QB64 VAL()." ELSE PRINT " " + LTRIM$(STR$(VAL(a1$) - VAL(b1$))), "QB64 VAL()."
            PRINT " "; z$, "String Math."
            PRINT
            sign$ = "": sign_a$ = "": sign_b$ = "": i&& = 0: j&& = 0: decimal% = 0: c = 0
    END SELECT
LOOP
SYSTEM

SUB string_compare (compa$, compb$, gl%)
    DO
        REM Remove trailing zeros after a decimal point.
        IF INSTR(compa$, ".") THEN
            DO UNTIL RIGHT$(compa$, 1) <> "0" AND RIGHT$(compa$, 1) <> "." AND RIGHT$(compa$, 1) <> "-"
                compa$ = MID$(compa$, 1, LEN(compa$) - 1)
            LOOP
        END IF
        IF INSTR(compb$, ".") THEN
            DO UNTIL RIGHT$(compb$, 1) <> "0" AND RIGHT$(compb$, 1) <> "." AND RIGHT$(compb$, 1) <> "-"
                compb$ = MID$(compb$, 1, LEN(compb$) - 1)
            LOOP
        END IF

        IF MID$(compa$, 1, 2) = "-0" OR compa$ = "" OR compa$ = "-" THEN compa$ = "0"
        IF MID$(compb$, 1, 2) = "-0" OR compb$ = "" OR compb$ = "-" THEN compb$ = "0"

        ' A - and +
        IF LEFT$(compa$, 1) = "-" THEN j% = -1
        IF LEFT$(compb$, 1) = "-" THEN k% = -1
        IF k% = 0 AND j% THEN gl% = -1: EXIT DO
        IF j% = 0 AND k% THEN gl% = 1: EXIT DO

        ' A decimal and non-decimal.
        j% = INSTR(compa$, ".")
        k% = INSTR(compb$, ".")
        IF j% = 0 AND k% THEN
            IF compa$ = "0" THEN gl% = -1 ELSE gl% = 1
            EXIT DO
        END IF
        IF k% = 0 AND j% THEN
            IF compb$ = "0" THEN gl% = 1 ELSE gl% = -1
            EXIT DO
        END IF

        ' Both decimals.
        IF j% THEN
            IF compa$ > compb$ THEN
                gl% = 1
            ELSEIF compa$ = compb$ THEN gl% = 0
            ELSEIF compa$ < compb$ THEN gl% = -1
            END IF
            EXIT DO
        END IF

        ' Both positive or both negative whole numbers.
        SELECT CASE LEN(compa$)
            CASE IS < LEN(compb$)
                gl% = -1
            CASE IS = LEN(compb$)
                IF compa$ = compb$ THEN
                    gl% = 0
                ELSEIF compa$ > compb$ THEN gl% = 1
                ELSEIF compa$ < compb$ THEN gl% = -1
                END IF
            CASE IS > LEN(compb$)
                gl% = 1
        END SELECT
        EXIT DO
    LOOP
END SUB

Edit fixed one bug by adding the statement: IF LEN(a$) < LEN(b$) THEN SWAP a$, b$

Pete
Reply
#16
When dealing with division, I've found that the way to do it in "chunks" is just like I described for the SQRT method above.

Get a seed using floating point math for an estimate, and then basically multiply on a binary system and zoom in on your decimal values.

Say your next 9 digits are "123456789" in the answer.

Multiply (EA$ + _TRIM$(STR$(500000000))) by your divisor and compare if the result too large or too small. (EA$ is your Existing Answer that you've calculated.) In this case, it's too large.

Half the gap, try again. (250000000) Too large
Half the gap, try again. (125000000) Too large
Half the gap, try again. (062500000) Too small
Half the gap...

You seek the result based on a binary search of basically a value from 0 to 999999999.... at most 30 multiplication runs will get you the answer. 2 ^ 30 is > 999,999,999. And that gives 9 digits to the answer at a time.

There might be a better way to do it, but if so, my brain isn't coming up with it. When dealing with obscene values like dividing (37 digits with 14 decimal places) into a (1234 digit with 36 decimal place) value, I just can't comprehend an easier way towards the solution.
Reply
#17
I punted on the idea of estimate methods because of accuracy. When working with 200+ decimal places I would think it would take longer to form estimates than to grind out long division.

Oh, speaking of square root calculations, I did manage one with my older string math single digit turning method...

Code: (Select All)
$CHECKING:OFF
WIDTH 160, 42
_SCREENMOVE 0, 0
DO
    limit&& = 32
    'betatest% = -1
    IF betatest% THEN limit&& = 16

    DO
        INPUT "Number: "; x$: PRINT

        IF x$ = "" THEN SYSTEM

        IF LEFT$(x$, 1) = "-" THEN
            PRINT "Negatives not allowed. Redo..": _DELAY 2: PRINT
        ELSE
            validate_string x$
            IF INSTR(x$, "invalid") = 0 THEN EXIT DO
            PRINT "Sorry, "; x$: _DELAY 1: PRINT
        END IF
    LOOP

    x# = VAL(x$) ' Needed for QB64 SQR() comparison only.
    oldy$ = ""

    IF INSTR(x$, ".") THEN
        decx$ = MID$(x$, 1, INSTR(x$, ".") - 1)
        x$ = MID$(x$, 1, INSTR(x$, ".") - 1) + MID$(x$, INSTR(x$, ".") + 1)
        IF LEN(x$) = 1 THEN x$ = x$ + "0"
    ELSE
        decx$ = x$
    END IF

    j&& = LEN(decx$)

    ' VAL() okay, one character eval.
    IF VAL(RIGHT$(LTRIM$(STR$(j&&)), 1)) / 2 = VAL(RIGHT$(LTRIM$(STR$(j&&)), 1)) \ 2 THEN
        i&& = 1 ' Even number length.
    ELSE
        i&& = 0 ' Odd number length.
    END IF

    DO
        stringmatha$ = z$: stringmathb$ = k$
        string_math z$, "-", k$, runningtotal$, terminating_decimal%, limit&&
        z$ = runningtotal$ + (MID$(x$, i&&, 2))
        IF LEFT$(z$, 1) = "0" THEN z$ = MID$(z$, 2) ' Remove leading zeros

        oldy$ = ""
        FOR j&& = 1 TO 10
            IF i&& > 1 THEN
                string_math sqrt$, "*", "2", y$, terminating_decimal%, limit&&
                y$ = y$ + LTRIM$(STR$(j&&))
            ELSE
                y$ = LTRIM$(STR$(j&&))
            END IF

            string_math y$, "*", LTRIM$(STR$(j&&)), runningtotal$, terminating_decimal%, limit&&

            string_compare runningtotal$, z$, gl%
            IF gl% > -1 THEN
                IF gl% = 0 THEN
                    h% = 0: oldy$ = y$ ' Perfect square division.
                ELSE
                    h% = 1
                END IF

                string_math oldy$, "*", LTRIM$(STR$(j&& - h%)), runningtotal$, terminating_decimal%, limit&&
                IF STRING$(LEN(z$), "0") = z$ AND runningtotal$ = "0" AND i&& >= LEN(decx$) THEN EXIT DO

                IF dp&& = 0 THEN ' Limited to && size unless converted to string.
                    IF i&& >= LEN(decx$) THEN
                        dp&& = INT(LEN(decx$) / 2 + .5)
                        IF dp&& = 0 THEN dp&& = -1
                    END IF
                END IF

                IF betatest% THEN PRINT "Sqrt "; sqrt$; " * 2 = ";: COLOR 2, 0: PRINT LTRIM$(STR$(VAL(sqrt$) * 2));: COLOR 7, 0: PRINT LTRIM$(STR$(j&& - h%)); " * "; LTRIM$(STR$(j&& - h%)); " ="; VAL(oldy$) * (j&& - h%)
                sqrt$ = sqrt$ + LTRIM$(STR$(j&& - h%))

                string_math oldy$, "*", LTRIM$(STR$(j&& - h%)), runningtotal$, terminating_decimal%, limit&&
                k$ = runningtotal$

                IF betatest% THEN PRINT "Remainder "; z$; " minus "; k$; " = ";
                EXIT FOR
            END IF
            oldy$ = y$
        NEXT

        IF betatest% THEN
            string_math stringmatha$, "-", stringmathb$, runningtotal$, terminating_decimal%, limit&&
            PRINT runningtotal$; " sqrt = "; sqrt$
        END IF

        i&& = i&& + 2
        IF LEN(z$) >= limit&& THEN EXIT DO
        x$ = x$ + "00"
    LOOP

    PRINT

    IF dp&& THEN
        sqrt$ = MID$(sqrt$, 0, dp&& + 1) + "." + MID$(sqrt$, dp&& + 1)
    END IF

    _CLIPBOARD$ = sqrt$
    PRINT "QB64 SQR:"; SQR(x#)
    PRINT "Pete SQR: "; sqrt$: _DELAY 1: CLEAR
    PRINT
LOOP

SUB string_math (stringmatha$, operator$, stringmathb$, runningtotal$, terminating_decimal%, limit&&)
    SELECT CASE operator$
        CASE "+", "-"
            GOTO string_add_subtract
        CASE "*"
            GOTO string_multiply
        CASE "/"
            GOTO string_divide
        CASE ELSE
            PRINT "Error, no operator selected. operator$ = "; operator$
    END SELECT

    string_divide:
    terminating_decimal% = 0: divsign% = 0: divremainder& = 0: divremainder$ = "": divplace& = 0: divplace2& = 0: quotient$ = "": divcarry& = 0
    operationdivision% = -1
    divbuffer& = LEN(stringmathb$) - LEN(stringmatha$)
    IF divbuffer& < 0 THEN divbuffer& = 0
    d2dividend$ = stringmatha$
    d1divisor$ = stringmathb$
    IF LEFT$(d1divisor$, 1) = "0" AND LEN(d1divisor$) = 1 THEN PRINT "Division by zero not allowed.": divsign% = 0: operationdivision% = 0: EXIT SUB
    IF LEFT$(d1divisor$, 1) = "-" THEN divsign% = -1: d1divisor$ = MID$(d1divisor$, 2)
    IF LEFT$(d2dividend$, 1) = "-" THEN
        IF divsign% THEN
            divsign% = 0
        ELSE
            divsign% = -1
        END IF
        d2dividend$ = MID$(d2dividend$, 2)
    END IF
    IF INSTR(d1divisor$, ".") <> 0 THEN
        DO UNTIL RIGHT$(d1divisor$, 1) <> "0"
            d1divisor$ = MID$(d1divisor$, 1, LEN(d1divisor$) - 1) ' Strip off trailing zeros
        LOOP
        divplace& = LEN(d1divisor$) - INSTR(d1divisor$, ".")
        d1divisor$ = MID$(d1divisor$, 1, INSTR(d1divisor$, ".") - 1) + MID$(d1divisor$, INSTR(d1divisor$, ".") + 1) ' Strip off decimal point.
        DO UNTIL LEFT$(d1divisor$, 1) <> "0"
            d1divisor$ = MID$(d1divisor$, 2) ' Strip off leading zeros for divisors smaller than .1
        LOOP
    END IF

    IF INSTR(d2dividend$, ".") <> 0 THEN
        d2dividend$ = d2dividend$ + STRING$(divplace& - LEN(d2dividend$) - INSTR(d2dividend$, "."), "0") ' Add any zeros based on the length of dividend at decimal - length of divisor at decimal. If less than zero, nothing added.
        divplace2& = INSTR(d2dividend$, ".")
        DO UNTIL RIGHT$(d2dividend$, 1) <> "0"
            d2dividend$ = MID$(d2dividend$, 1, LEN(d2dividend$) - 1) ' Strip off trailing zeros
        LOOP
        d2dividend$ = MID$(d2dividend$, 1, INSTR(d2dividend$, ".") - 1) + MID$(d2dividend$, INSTR(d2dividend$, ".") + 1) ' Strip off decimal point.
    ELSE
        d2dividend$ = d2dividend$ + STRING$(divplace&, "0") ' Add any zeros based on the length of dividend at decimal - length of divisor at decimal. If less than zero, nothing added.
        divplace& = 0
    END IF
    DO
        DO
            divremainder& = divremainder& + 1: divremainder$ = divremainder$ + MID$(d2dividend$, divremainder&, 1)
            IF MID$(d2dividend$, divremainder&, 1) = "" THEN
                IF divremainder$ = STRING$(LEN(divremainder$), "0") AND LEN(quotient$) > LEN(d2dividend$) THEN
                    divflag% = -1
                    terminating_decimal% = -1
                    EXIT DO
                END IF
                divcarry& = divcarry& + 1
                IF divcarry& = 1 THEN divplace3& = divremainder& - 1
                IF divcarry& > limit&& + 1 + divbuffer& THEN
                    divflag% = -2: EXIT DO
                END IF
                divremainder$ = divremainder$ + "0" ' No more digits to bring down.
            END IF
            IF LEN(divremainder$) > LEN(d1divisor$) OR LEN(divremainder$) = LEN(d1divisor$) AND divremainder$ >= d1divisor$ THEN EXIT DO
            quotient$ = quotient$ + "0"
        LOOP
        IF divflag% THEN divflag% = 0: EXIT DO
        FOR div_i% = 9 TO 1 STEP -1
            stringmatha$ = LTRIM$(STR$(div_i%)): stringmathb$ = d1divisor$
            m_product$ = "": GOSUB string_multiply
            tempcutd$ = divremainder$ ' divremainder$ can be 00 or other leading zero values.
            DO
                IF LEN(tempcutd$) = 1 THEN EXIT DO
                IF LEFT$(tempcutd$, 1) = "0" THEN
                    tempcutd$ = MID$(tempcutd$, 2)
                ELSE
                    EXIT DO
                END IF
            LOOP
            IF LEN(tempcutd$) > LEN(m_product$) OR LEN(tempcutd$) = LEN(m_product$) AND m_product$ <= tempcutd$ THEN EXIT FOR
        NEXT
        quotient$ = quotient$ + LTRIM$(STR$(div_i%))
        stringmatha$ = LTRIM$(STR$(div_i%)): stringmathb$ = d1divisor$
        m_product$ = "": GOSUB string_multiply
        operator$ = "-"
        stringmatha$ = divremainder$
        stringmathb$ = m_product$
        GOSUB string_add_subtract
        divremainder$ = stringmatha$
        operator$ = "/"
    LOOP
    IF divplace& = 0 AND divplace2& = 0 THEN divplace& = divplace3&
    IF divplace2& THEN divplace& = divplace& + divplace2& - 1
    IF quotient$ = "" THEN divplace& = 0 ' dividend is zero.
    IF divplace& OR divplace2& THEN
        quotient$ = MID$(quotient$, 1, divplace&) + "." + MID$(quotient$, divplace& + 1)
        DO UNTIL RIGHT$(quotient$, 1) <> "0"
            quotient$ = MID$(quotient$, 1, LEN(quotient$) - 1) ' Strip off trailing zeros
        LOOP
        IF RIGHT$(quotient$, 1) = "." THEN quotient$ = MID$(quotient$, 1, LEN(quotient$) - 1) ' Strip off abandoned decimal.
    END IF
    DO UNTIL LEFT$(quotient$, 1) <> "0"
        quotient$ = MID$(quotient$, 2) ' Strip off leading zeros
    LOOP
    IF quotient$ = "" THEN quotient$ = "0": divsign% = 0
    operationdivision% = 0
    stringmathb$ = quotient$: quotient$ = ""

    IF stringmathb$ = "overflow" THEN divsign% = 0: operationdivision% = 0: EXIT SUB

    runningtotal$ = stringmathb$: stringmathb$ = ""
    IF divsign% THEN runningtotal$ = "-" + runningtotal$

    IF stringmathround$ <> "" THEN runningtotal$ = runningtotal$ + stringmathround$
    operationdivision% = 0
    EXIT SUB

    string_multiply:
    m_decimal_places& = 0: m_product$ = ""
    fac1$ = stringmatha$: fac2$ = stringmathb$ ' Make numbers whole numbers and remove any - sign.
    IF LEFT$(fac1$, 1) = "-" THEN fac1$ = MID$(fac1$, 2): m_sign% = -1
    IF LEFT$(fac2$, 1) = "-" THEN fac2$ = MID$(fac2$, 2): IF m_sign% THEN m_sign% = 0 ELSE m_sign% = -1
    IF INSTR(fac1$, ".") <> 0 THEN m_decimal_places& = LEN(fac1$) - INSTR(fac1$, "."): fac1$ = MID$(fac1$, 1, INSTR(fac1$, ".") - 1) + MID$(fac1$, INSTR(fac1$, ".") + 1)
    IF INSTR(fac2$, ".") <> 0 THEN m_decimal_places& = m_decimal_places& + LEN(fac2$) - INSTR(fac2$, "."): fac2$ = MID$(fac2$, 1, INSTR(fac2$, ".") - 1) + MID$(fac2$, INSTR(fac2$, ".") + 1)
    FOR m_i& = LEN(fac2$) TO 1 STEP -1 ' Multiply each charater top and bottom.
        m_k& = m_l&
        m_x2$ = MID$(fac2$, m_i&, 1)
        FOR m_j& = LEN(fac1$) TO 1 STEP -1
            m_x1$ = MID$(fac1$, m_j&, 1)
            IF m_product$ <> "" THEN
                m_add$ = LTRIM$(STR$(VAL(m_x1$) * VAL(m_x2$))) + STRING$(m_k&, "0")
                m_t& = 0: m_xproduct$ = "": m_carry% = 0
                DO ' Add multiplied characters together.
                    m_x3$ = MID$(m_add$, LEN(m_add$) - m_t&, 1)
                    m_x4$ = MID$(m_product$, LEN(m_product$) - m_t&, 1)
                    IF m_x3$ = "" AND m_x4$ = "" THEN
                        IF m_carry% THEN m_xproduct$ = "1" + m_xproduct$
                        EXIT DO
                    END IF
                    m_g% = VAL(m_x3$) + VAL(m_x4$) + m_carry%
                    IF m_g% >= 10 THEN m_g% = m_g% - 10: m_carry% = 1 ELSE m_carry% = 0
                    m_xproduct$ = LTRIM$(STR$(m_g%)) + m_xproduct$
                    m_t& = m_t& + 1
                LOOP
                m_product$ = m_xproduct$: m_xproduct$ = ""
            ELSE
                m_product$ = LTRIM$(STR$(VAL(m_x1$) * VAL(m_x2$))) + STRING$(m_k&, "0") ' First loop makes variable here.
            END IF
            m_k& = m_k& + 1 ' Adds trailing zeros multiplication
        NEXT
        m_l& = m_l& + 1 ' Used to reset value for m_k& adding one trailing zer for each loop.
    NEXT
    fac1$ = "": fac2$ = "": m_l& = 0: m_k& = 0: m_t& = 0
    IF m_decimal_places& > LEN(m_product$) THEN m_product$ = STRING$(m_decimal_places& - LEN(m_product$), "0") + m_product$ ' Add any leading zeros to a decimal. Ex: .02 * .01 is factored as 002. It needs one leading zero before adding the decimal point, .0002.
    IF m_decimal_places& AND m_product$ <> "0" THEN ' Replace any decimal point.
        m_product$ = MID$(m_product$, 1, LEN(m_product$) - m_decimal_places&) + "." + MID$(m_product$, LEN(m_product$) - m_decimal_places& + 1)
    END IF
    DO UNTIL LEFT$(m_product$, 1) <> "0" ' Remove leading zeros.
        m_product$ = MID$(m_product$, 2)
    LOOP
    IF m_decimal_places& THEN
        DO UNTIL RIGHT$(m_product$, 1) <> "0" ' Remove trailing zeros in a decimal sum.
            m_product$ = MID$(m_product$, 1, LEN(m_product$) - 1)
        LOOP
    END IF
    IF m_product$ = "" THEN m_product$ = "0": m_sign% = 0
    IF RIGHT$(m_product$, 1) = "." THEN m_product$ = MID$(m_product$, 1, LEN(m_product$) - 1) ' Remove decimal from the end of an integer total.
    IF operationdivision% THEN m_sign% = 0: RETURN
    stringmathb$ = m_product$: m_product$ = ""

    IF stringmathb$ = "overflow" THEN EXIT SUB

    runningtotal$ = stringmathb$: stringmathb$ = ""
    IF m_sign% THEN runningtotal$ = "-" + runningtotal$: m_sign% = 0
    EXIT SUB

    string_add_subtract:
    IF INSTR(stringmatha$, ".") <> 0 THEN ' Evaluate sum for decimal fraction.
        sumplace& = LEN(stringmatha$) - INSTR(stringmatha$, ".")
        stringmatha$ = MID$(stringmatha$, 1, INSTR(stringmatha$, ".") - 1) + MID$(stringmatha$, INSTR(stringmatha$, ".") + 1) ' Strip out decimal
    END IF
    IF INSTR(stringmathb$, ".") <> 0 THEN ' Evaluate number for decimal fraction.
        numplace& = LEN(stringmathb$) - INSTR(stringmathb$, ".")
        stringmathb$ = MID$(stringmathb$, 1, INSTR(stringmathb$, ".") - 1) + MID$(stringmathb$, INSTR(stringmathb$, ".") + 1) ' Strip out decimal
    END IF
    IF sumplace& > numplace& THEN addsubplace& = sumplace& ELSE addsubplace& = numplace&
    IF sumplace& > addsubplace& THEN
        stringmatha$ = stringmatha$ + STRING$(sumplace& - addsubplace&, "0")
    ELSEIF addsubplace& > sumplace& THEN
        stringmatha$ = stringmatha$ + STRING$(addsubplace& - sumplace&, "0")
    END IF
    IF numplace& > addsubplace& THEN
        stringmathb$ = stringmathb$ + STRING$(numplace& - addsubplace&, "0")
    ELSEIF addsubplace& > numplace& THEN
        stringmathb$ = stringmathb$ + STRING$(addsubplace& - numplace&, "0")
    END IF ' END Decimal evaluations.

    IF LEFT$(stringmatha$, 1) = "-" THEN sign_input$ = "-" ELSE sign_input$ = "+"
    IF LEFT$(stringmathb$, 1) = "-" THEN sign_total$ = "-" ELSE sign_total$ = "+"

    addsubsign% = 0
    SELECT CASE sign_input$ + operator$ + sign_total$
        CASE "+++", "+--"
            operator$ = "+"
            IF LEFT$(stringmathb$, 1) = "-" THEN stringmathb$ = MID$(stringmathb$, 2)
        CASE "++-", "+-+"
            operator$ = "-"
            IF LEFT$(stringmathb$, 1) = "-" THEN stringmathb$ = MID$(stringmathb$, 2)
            GOSUB string_comp
            IF gl% < 0 THEN SWAP stringmatha$, stringmathb$: addsubsign% = -1
        CASE "---", "-++"
            operator$ = "-"
            IF LEFT$(stringmatha$, 1) = "-" THEN stringmatha$ = MID$(stringmatha$, 2)
            IF LEFT$(stringmathb$, 1) = "-" THEN stringmathb$ = MID$(stringmathb$, 2)
            GOSUB string_comp
            IF gl% < 0 THEN SWAP stringmatha$, stringmathb$: addsubsign% = -1
        CASE "--+", "-+-"
            operator$ = "+"
            IF LEFT$(stringmatha$, 1) = "-" THEN stringmatha$ = MID$(stringmatha$, 2)
            IF LEFT$(stringmathb$, 1) = "-" THEN stringmathb$ = MID$(stringmathb$, 2)
            addsubsign% = -1
    END SELECT

    IF LEN(stringmatha$) > LEN(stringmathb$) THEN
        stringmathb$ = STRING$(LEN(stringmatha$) - LEN(stringmathb$), "0") + stringmathb$
    ELSEIF LEN(stringmatha$) < LEN(stringmathb$) THEN
        stringmatha$ = STRING$(LEN(stringmathb$) - LEN(stringmatha$), "0") + stringmatha$
    END IF
    addsubx1$ = ""

    SELECT CASE operator$
        CASE "+", "="
            FOR addsubii& = LEN(stringmatha$) TO 1 STEP -1
                addsubx1% = VAL(MID$(stringmatha$, addsubii&, 1)) + VAL(MID$(stringmathb$, addsubii&, 1)) + addsubcarry%
                IF addsubx1% > 9 THEN addsubx1% = addsubx1% - 10: addsubcarry% = 1 ELSE addsubcarry% = 0
                addsubx1$ = LTRIM$(STR$(addsubx1%)) + addsubx1$
            NEXT
            IF addsubcarry% THEN addsubx1$ = "1" + addsubx1$: addsubcarry% = 0
            GOSUB replace_decimal
        CASE "-"
            FOR addsubii& = LEN(stringmatha$) TO 1 STEP -1
                addsubx1% = VAL(MID$(stringmatha$, addsubii&, 1)) - VAL(MID$(stringmathb$, addsubii&, 1)) + addsubcarry%
                IF addsubx1% < 0 THEN addsubx1% = addsubx1% + 10: addsubcarry% = -1 ELSE addsubcarry% = 0
                addsubx1$ = LTRIM$(STR$(addsubx1%)) + addsubx1$
            NEXT
            IF addsubx1$ <> "" AND addsubx1$ <> STRING$(LEN(addsubx1$), "0") THEN GOSUB replace_decimal
            DO UNTIL LEFT$(addsubx1$, 1) <> "0" ' Remove leading zeros.
                addsubx1$ = MID$(addsubx1$, 2)
            LOOP
            IF addsubx1$ = "" THEN
                addsubx1$ = "0": addsubsign% = 0
            ELSE
                IF addsubcarry% THEN addsubx1$ = "-" + addsubx1$: addsubcarry% = 0
            END IF
    END SELECT

    IF addsubsign% THEN
        IF LEFT$(addsubx1$, 1) = "-" THEN addsubx1$ = MID$(addsubx1$, 2) ELSE addsubx1$ = "-" + addsubx1$
    END IF
    stringmatha$ = addsubx1$: addsubx1$ = ""
    IF operationdivision% THEN RETURN
    stringmathb$ = stringmatha$: stringmatha$ = ""
    IF LEFT$(stringmathb$, 1) = "-" THEN
        stringmathb$ = MID$(stringmathb$, 2)
        n2sign$ = "-"
    ELSE
        n2sign$ = ""
    END IF

    IF stringmathb$ = "overflow" THEN n2sign$ = "": EXIT SUB

    runningtotal$ = n2sign$ + stringmathb$: n2sign$ = ""
    EXIT SUB

    replace_decimal:
    IF addsubplace& THEN
        addsubx1$ = STRING$(addsubplace& - LEN(addsubx1$), "0") + addsubx1$
        addsubx1$ = MID$(addsubx1$, 1, LEN(addsubx1$) - addsubplace&) + "." + MID$(addsubx1$, LEN(addsubx1$) - addsubplace& + 1)
        DO UNTIL RIGHT$(addsubx1$, 1) <> "0" ' Remove trailing zeros in a decimal sum.
            addsubx1$ = MID$(addsubx1$, 1, LEN(addsubx1$) - 1)
            addsubplace& = addsubplace& - 1
        LOOP
        IF RIGHT$(addsubx1$, 1) = "." THEN addsubx1$ = MID$(addsubx1$, 1, LEN(addsubx1$) - 1) ' Number is now an integer.
    END IF
    RETURN

    string_comp:
    DO
        REM Remove trailing zeros after a decimal point.
        IF INSTR(acomp$, ".") THEN
            DO UNTIL RIGHT$(acomp$, 1) <> "0" AND RIGHT$(acomp$, 1) <> "." AND RIGHT$(acomp$, 1) <> "-"
                acomp$ = MID$(acomp$, 1, LEN(acomp$) - 1)
            LOOP
        END IF
        IF INSTR(bcomp$, ".") THEN
            DO UNTIL RIGHT$(bcomp$, 1) <> "0" AND RIGHT$(bcomp$, 1) <> "." AND RIGHT$(bcomp$, 1) <> "-"
                bcomp$ = MID$(bcomp$, 1, LEN(bcomp$) - 1)
            LOOP
        END IF

        IF MID$(acomp$, 1, 2) = "-0" OR acomp$ = "" OR acomp$ = "-" THEN acomp$ = "0"
        IF MID$(bcomp$, 1, 2) = "-0" OR bcomp$ = "" OR bcomp$ = "-" THEN bcomp$ = "0"

        ' A - and +
        IF LEFT$(acomp$, 1) = "-" THEN j% = -1
        IF LEFT$(bcomp$, 1) = "-" THEN k% = -1
        IF k% = 0 AND j% THEN gl% = -1: EXIT DO
        IF j% = 0 AND k% THEN gl% = 1: EXIT DO

        ' A decimal and non-decimal.
        j% = INSTR(acomp$, ".")
        k% = INSTR(bcomp$, ".")
        IF j% = 0 AND k% THEN
            IF acomp$ = "0" THEN gl% = -1 ELSE gl% = 1
            EXIT DO
        END IF
        IF k% = 0 AND j% THEN
            IF bcomp$ = "0" THEN gl% = 1 ELSE gl% = -1
            EXIT DO
        END IF

        ' Both decimals.
        IF j% THEN
            IF acomp$ > bcomp$ THEN
                gl% = 1
            ELSEIF acomp$ = bcomp$ THEN gl% = 0
            ELSEIF acomp$ < bcomp$ THEN gl% = -1
            END IF
            EXIT DO
        END IF

        ' Both positive or both negative whole numbers.
        SELECT CASE LEN(acomp$)
            CASE IS < LEN(bcomp$)
                gl% = -1
            CASE IS = LEN(bcomp$)
                IF acomp$ = bcomp$ THEN
                    gl% = 0
                ELSEIF acomp$ > bcomp$ THEN gl% = 1
                ELSEIF acomp$ < bcomp$ THEN gl% = -1
                END IF
            CASE IS > LEN(bcomp$)
                gl% = 1
        END SELECT
        EXIT DO
    LOOP
    RETURN
END SUB

SUB string_compare (compa$, compb$, gl%)
    DO
        REM Remove trailing zeros after a decimal point.
        IF INSTR(compa$, ".") THEN
            DO UNTIL RIGHT$(compa$, 1) <> "0" AND RIGHT$(compa$, 1) <> "." AND RIGHT$(compa$, 1) <> "-"
                compa$ = MID$(compa$, 1, LEN(compa$) - 1)
            LOOP
        END IF
        IF INSTR(compb$, ".") THEN
            DO UNTIL RIGHT$(compb$, 1) <> "0" AND RIGHT$(compb$, 1) <> "." AND RIGHT$(compb$, 1) <> "-"
                compb$ = MID$(compb$, 1, LEN(compb$) - 1)
            LOOP
        END IF

        IF MID$(compa$, 1, 2) = "-0" OR compa$ = "" OR compa$ = "-" THEN compa$ = "0"
        IF MID$(compb$, 1, 2) = "-0" OR compb$ = "" OR compb$ = "-" THEN compb$ = "0"

        ' A - and +
        IF LEFT$(compa$, 1) = "-" THEN j% = -1
        IF LEFT$(compb$, 1) = "-" THEN k% = -1
        IF k% = 0 AND j% THEN gl% = -1: EXIT DO
        IF j% = 0 AND k% THEN gl% = 1: EXIT DO

        ' A decimal and non-decimal.
        j% = INSTR(compa$, ".")
        k% = INSTR(compb$, ".")
        IF j% = 0 AND k% THEN
            IF compa$ = "0" THEN gl% = -1 ELSE gl% = 1
            EXIT DO
        END IF
        IF k% = 0 AND j% THEN
            IF compb$ = "0" THEN gl% = 1 ELSE gl% = -1
            EXIT DO
        END IF

        ' Both decimals.
        IF j% THEN
            IF compa$ > compb$ THEN
                gl% = 1
            ELSEIF compa$ = compb$ THEN gl% = 0
            ELSEIF compa$ < compb$ THEN gl% = -1
            END IF
            EXIT DO
        END IF

        ' Both positive or both negative whole numbers.
        SELECT CASE LEN(compa$)
            CASE IS < LEN(compb$)
                gl% = -1
            CASE IS = LEN(compb$)
                IF compa$ = compb$ THEN
                    gl% = 0
                ELSEIF compa$ > compb$ THEN gl% = 1
                ELSEIF compa$ < compb$ THEN gl% = -1
                END IF
            CASE IS > LEN(compb$)
                gl% = 1
        END SELECT
        EXIT DO
    LOOP
END SUB

SUB validate_string (stringmathb$)
    DO ' Faux loop.
        vsn_negcnt& = 0: vsn_poscnt& = 0: vsn_depresent& = 0: decimalcnt& = 0: vsn_numberpresent& = 0: vsn_zerospresent& = 0
        IF LEFT$(stringmathb$, 1) = "-" THEN stringmathb$ = MID$(stringmathb$, 2): sm_sign$ = "-" ELSE sm_sign$ = ""
        IF LEFT$(stringmathb$, 1) = "+" THEN IF sm_sign$ <> "-" THEN stringmathb$ = MID$(stringmathb$, 2) ELSE stringmathb$ = "invalid number": EXIT DO
        IF INSTR(UCASE$(stringmathb$), "D") OR INSTR(UCASE$(stringmathb$), "E") THEN ' Evaluate for Scientific Notation.
            FOR sm_i& = 1 TO LEN(stringmathb$)
                validatenum$ = MID$(UCASE$(stringmathb$), sm_i&, 1)
                SELECT CASE validatenum$
                    CASE "+"
                        IF vsn_depresent& THEN vsn_poscnt& = vsn_poscnt& + 1 ELSE stringmathb$ = "invalid number": EXIT DO
                    CASE "-"
                        IF vsn_depresent& THEN vsn_negcnt& = vsn_negcnt& + 1 ELSE stringmathb$ = "invalid number": EXIT DO
                    CASE "0" TO "9"
                        vsn_numberpresent& = -1
                    CASE "D", "E"
                        vsn_depresent& = vsn_depresent& + 1
                        IF decimalcnt& = 0 AND sm_i& <> 2 OR vsn_depresent& > 1 OR vsn_numberpresent& = 0 OR vsn_negcnt& > 1 OR vsn_poscnt& > 1 OR vsn_negcnt& = 1 AND vsn_poscnt& >= 1 THEN vsn_numberpresent& = 0: EXIT FOR
                        vsn_numberpresent& = 0
                        MID$(stringmathb$, sm_i&, 1) = "e" ' Standardize
                    CASE "."
                        decimalcnt& = decimalcnt& + 1
                        IF sm_i& <> 2 THEN vsn_numberpresent& = 0: EXIT FOR
                    CASE ELSE
                        vsn_numberpresent& = 0: EXIT FOR
                END SELECT
            NEXT
            IF decimalcnt& = 0 THEN stringmathb$ = MID$(stringmathb$, 1, 1) + "." + MID$(stringmathb$, 2) ' Standardize "."
            IF vsn_numberpresent& = 0 OR vsn_negcnt& = 1 AND vsn_poscnt& = 1 OR decimalcnt& > 1 OR INSTR(stringmathb$, ".") <> 2 THEN stringmathb$ = "invalid number": EXIT DO
            vsn_depresent& = INSTR(stringmathb$, "e")
            sm_x$ = MID$(stringmathb$, vsn_depresent& + 1, 1) ' Standardize exponent "+" these two lines.
            IF sm_x$ <> "+" AND sm_x$ <> "-" THEN stringmathb$ = MID$(stringmathb$, 1, vsn_depresent&) + "+" + MID$(stringmathb$, vsn_depresent& + 1)
            IF MID$(stringmathb$, vsn_depresent& + 2, 1) = "0" THEN
                IF MID$(stringmathb$, vsn_depresent& + 3, 1) <> "" THEN stringmathb$ = "invalid number": EXIT DO ' No leading zeros allowed in exponent notation.
            END IF
            jjed& = INSTR(stringmathb$, "e") ' Get position of notation.
            valexpside$ = MID$(stringmathb$, jjed&) ' These two lines break up into number and notation
            stringmathb$ = MID$(stringmathb$, 1, jjed& - 1) ' stringmathb$ is +- single digit whole number, decimal point and decimal number. valexpside$ is notation, sign and exponent.
            DO UNTIL RIGHT$(stringmathb$, 1) <> "0" ' Remove any trailing zeros for number. Example 1.0d3 or 1.0000d3, etc.
                stringmathb$ = MID$(stringmathb$, 1, LEN(stringmathb$) - 1)
            LOOP
            IF VAL(MID$(stringmathb$, 1, INSTR(stringmathb$, ".") - 1)) = 0 THEN
                IF RIGHT$(stringmathb$, 1) = "." THEN
                    stringmathb$ = "0.e+0" ' Handles all types of zero entries.
                ELSE
                    stringmathb$ = "invalid number": EXIT DO
                END IF
                EXIT DO
            END IF
            stringmathb$ = sm_sign$ + stringmathb$ + valexpside$
            EXIT DO
        ELSE
            FOR sm_i& = 1 TO LEN(stringmathb$)
                validatenum$ = MID$(stringmathb$, sm_i&, 1)
                SELECT CASE validatenum$
                    CASE "."
                        decimalcnt& = decimalcnt& + 1
                    CASE "0"
                        vsn_zerospresent& = -1
                    CASE "1" TO "9"
                        vsn_numberpresent& = -1
                    CASE "$"
                    CASE ELSE
                        stringmathb$ = "invalid number": EXIT DO
                END SELECT
            NEXT
            IF decimalcnt& > 1 OR vsn_negcnt& > 1 OR vsn_poscnt& > 1 OR vsn_negcnt& >= 1 AND vsn_poscnt& >= 1 THEN
                stringmathb$ = "invalid number": EXIT DO
            END IF

            REM IF INSTR(stringmathb$, "$") THEN GOSUB currency_validate
            REM IF INSTR(stringmathb$, ",") THEN
            REM    GOSUB comma_validation
            REM IF stringmathb$ = "invalid number" THEN exit do
            REM GOSUB comma_removal
            REM END IF

            IF RIGHT$(stringmathb$, 1) = "." THEN stringmathb$ = MID$(stringmathb$, 1, LEN(stringmathb$) - 1)
            DO UNTIL LEFT$(stringmathb$, 1) <> "0" ' Strip off any leading zeros.
                stringmathb$ = MID$(stringmathb$, 2)
            LOOP
            stringmathb$ = sm_sign$ + stringmathb$
            IF INSTR(stringmathb$, ".") THEN
                DO UNTIL RIGHT$(stringmathb$, 1) <> "0" ' Strip off any trailing zeros in a decimal.
                    stringmathb$ = MID$(stringmathb$, 1, LEN(stringmathb$) - 1)
                LOOP
            END IF
            IF RIGHT$(stringmathb$, 1) = "." THEN stringmathb$ = MID$(stringmathb$, 1, LEN(stringmathb$) - 1)
            IF vsn_numberpresent& = 0 THEN
                IF vsn_zerospresent& THEN
                    stringmathb$ = "0"
                ELSE
                    stringmathb$ = "invalid number"
                END IF
            END IF
        END IF
        EXIT DO
    LOOP
END SUB

Pete
If eggs are brain food, Biden takes his scrambled.
Reply
#18
Here's a way which seems like it'd be mighty speed to me -- and it doesn't take any multiplication after a 1 run look-up table!

Make an array from 0 to 9.  (DIM foo(9) AS STRING)
Take your divisor and multiply it by 0 to 9.  Store the results.

For example, my divisor is 100.
foo(1) = 100
foo(2) = 200
...
foo(9) = 900)

With your lookup table, you now just grab chunks of your string and compare.

Write a SELECT CASE to find your value

SELECT CASE num2check$
    CASE < foo(1): dividend = 0
    CASE < foo(2): dividend = 1
    CASE < foo(3): dividend = 2
....
    CASE ELSE: dividend = 9
END SELECT

*******

In practice, let's use 123456789/ 3 as an easy example:
f1 = 3
f2 = 6
f3 = 9
... you get the array....

start with the first digit: 1...  smaller than f1, result is 0. 1 - 0 = 1 carryover
bring down the 2.  Value is now 12.  is smaller than f5, result is 4.  12 - 12 = 0 carryover
bring down the 3.  Carryover was 0, value is 3.  Less than f2, result is 1.  3 - 3 = 0
bring down the 4.  Carryover was 0, value is 4.  Less than f2, result is 1.  4 - 3 = 1 carryover
bring down the 5.  Carryover was 1, value is 15.  Less than f6, result is 5....
... and on.

Instead of doing that multiplication math over and over, do it once and store it in an array.  I imagine you'll save a boatload of time processing, if you do so.
Reply
#19
thanks Steve Smile
as for division, maybe this video will inspire you https://youtu.be/6bpLYxk9TUQ
website http://justinparrtech.com/JustinParr-Tec...#more-1632
Reply
#20
WOW! this is great. I fixed two bugs in my new string math routine after rigorous testing by incorporating it into my square root calculator. Then I substituted the debugged code to the square root calculator and the speed improvement was blinding!

So I did a test on the square root of 2 to 5,000 places. It only took 45 seconds on my slow clunky laptop.  If you like to try that out, change the limit&& variable to 5000, run the program, and input 2 at the number prompt.

Anyway, here's the square root program with the my new faster bulk number processing string math system.

Code: (Select All)
WIDTH 160, 42
_SCREENMOVE 0, 0
DO
    limit&& = 128
    'betatest% = -1
    IF betatest% THEN limit&& = 16

    DO
        INPUT "Number: "; x$: PRINT

        IF x$ = "" THEN SYSTEM

        IF LEFT$(x$, 1) = "-" THEN
            PRINT "Negatives not allowed. Redo..": _DELAY 2: PRINT
        ELSE
            validate_string x$
            IF INSTR(x$, "invalid") = 0 THEN EXIT DO
            PRINT "Sorry, "; x$: _DELAY 1: PRINT
        END IF
    LOOP

    x# = VAL(x$) ' Needed for QB64 SQR() comparison only.
    oldy$ = ""

    IF INSTR(x$, ".") THEN
        decx$ = MID$(x$, 1, INSTR(x$, ".") - 1)
        x$ = MID$(x$, 1, INSTR(x$, ".") - 1) + MID$(x$, INSTR(x$, ".") + 1)
        IF LEN(x$) = 1 THEN x$ = x$ + "0"
    ELSE
        decx$ = x$
    END IF

    j&& = LEN(decx$)

    ' VAL() okay, one character eval.
    IF VAL(RIGHT$(LTRIM$(STR$(j&&)), 1)) / 2 = VAL(RIGHT$(LTRIM$(STR$(j&&)), 1)) \ 2 THEN
        i&& = 1 ' Even number length.
    ELSE
        i&& = 0 ' Odd number length.
    END IF

    DO
        stringmatha$ = z$: stringmathb$ = k$
        string_math z$, "-", k$, runningtotal$, terminating_decimal%, limit&&
        z$ = runningtotal$ + (MID$(x$, i&&, 2))
        IF LEFT$(z$, 1) = "0" THEN z$ = MID$(z$, 2) ' Remove leading zeros

        oldy$ = ""
        FOR j&& = 1 TO 10
            IF i&& > 1 THEN
                string_math sqrt$, "*", "2", y$, terminating_decimal%, limit&&
                y$ = y$ + LTRIM$(STR$(j&&))
            ELSE
                y$ = LTRIM$(STR$(j&&))
            END IF

            string_math y$, "*", LTRIM$(STR$(j&&)), runningtotal$, terminating_decimal%, limit&&

            string_compare runningtotal$, z$, gl%
            IF gl% > -1 THEN
                IF gl% = 0 THEN
                    h% = 0: oldy$ = y$ ' Perfect square division.
                ELSE
                    h% = 1
                END IF
                string_math oldy$, "*", LTRIM$(STR$(j&& - h%)), runningtotal$, terminating_decimal%, limit&&
                IF STRING$(LEN(z$), "0") = z$ AND runningtotal$ = "0" AND i&& >= LEN(decx$) THEN EXIT DO

                IF dp&& = 0 THEN ' Limited to && size unless converted to string.
                    IF i&& >= LEN(decx$) THEN
                        dp&& = INT(LEN(decx$) / 2 + .5)
                        IF dp&& = 0 THEN dp&& = -1
                    END IF
                END IF

                IF betatest% THEN PRINT "Sqrt "; sqrt$; " * 2 = ";: COLOR 2, 0: PRINT LTRIM$(STR$(VAL(sqrt$) * 2));: COLOR 7, 0: PRINT LTRIM$(STR$(j&& - h%)); " * "; LTRIM$(STR$(j&& - h%)); " ="; VAL(oldy$) * (j&& - h%)
                sqrt$ = sqrt$ + LTRIM$(STR$(j&& - h%))

                string_math oldy$, "*", LTRIM$(STR$(j&& - h%)), runningtotal$, terminating_decimal%, limit&&
                k$ = runningtotal$

                IF betatest% THEN PRINT "Remainder "; z$; " minus "; k$; " = ";
                EXIT FOR
            END IF
            oldy$ = y$
        NEXT

        IF betatest% THEN
            string_math stringmatha$, "-", stringmathb$, runningtotal$, terminating_decimal%, limit&&
            PRINT runningtotal$; " sqrt = "; sqrt$
        END IF

        i&& = i&& + 2
        IF LEN(z$) >= limit&& THEN EXIT DO
        x$ = x$ + "00"
    LOOP

    PRINT

    IF dp&& THEN
        sqrt$ = MID$(sqrt$, 0, dp&& + 1) + "." + MID$(sqrt$, dp&& + 1)
    END IF

    _CLIPBOARD$ = sqrt$
    PRINT "QB64 SQR:"; SQR(x#)
    PRINT "Pete SQR: "; sqrt$: _DELAY 1: CLEAR
    PRINT
LOOP

SUB string_math (stringmatha$, operator$, stringmathb$, runningtotal$, terminating_decimal%, limit&&)
    DIM AS _INTEGER64 a, b, c, aa, bb, cc, s, ss
    a1$ = stringmatha$: b1$ = stringmathb$

    SELECT CASE operator$
        CASE "+", "-"
            GOTO string_add_subtract_new
        CASE "*"
            GOTO string_multiply_new
        CASE "/"
            GOTO string_divide
        CASE ELSE
            PRINT "Error, no operator selected. operator$ = "; operator$
    END SELECT

    string_divide:
    terminating_decimal% = 0: divsign% = 0: divremainder& = 0: divremainder$ = "": divplace& = 0: divplace2& = 0: quotient$ = "": divcarry& = 0
    operationdivision% = -1
    divbuffer& = LEN(stringmathb$) - LEN(stringmatha$)
    IF divbuffer& < 0 THEN divbuffer& = 0
    d2dividend$ = stringmatha$
    d1divisor$ = stringmathb$
    IF LEFT$(d1divisor$, 1) = "0" AND LEN(d1divisor$) = 1 THEN PRINT "Division by zero not allowed.": divsign% = 0: operationdivision% = 0: EXIT SUB
    IF LEFT$(d1divisor$, 1) = "-" THEN divsign% = -1: d1divisor$ = MID$(d1divisor$, 2)
    IF LEFT$(d2dividend$, 1) = "-" THEN
        IF divsign% THEN
            divsign% = 0
        ELSE
            divsign% = -1
        END IF
        d2dividend$ = MID$(d2dividend$, 2)
    END IF
    IF INSTR(d1divisor$, ".") <> 0 THEN
        DO UNTIL RIGHT$(d1divisor$, 1) <> "0"
            d1divisor$ = MID$(d1divisor$, 1, LEN(d1divisor$) - 1) ' Strip off trailing zeros
        LOOP
        divplace& = LEN(d1divisor$) - INSTR(d1divisor$, ".")
        d1divisor$ = MID$(d1divisor$, 1, INSTR(d1divisor$, ".") - 1) + MID$(d1divisor$, INSTR(d1divisor$, ".") + 1) ' Strip off decimal point.
        DO UNTIL LEFT$(d1divisor$, 1) <> "0"
            d1divisor$ = MID$(d1divisor$, 2) ' Strip off leading zeros for divisors smaller than .1
        LOOP
    END IF

    IF INSTR(d2dividend$, ".") <> 0 THEN
        d2dividend$ = d2dividend$ + STRING$(divplace& - LEN(d2dividend$) - INSTR(d2dividend$, "."), "0") ' Add any zeros based on the length of dividend at decimal - length of divisor at decimal. If less than zero, nothing added.
        divplace2& = INSTR(d2dividend$, ".")
        DO UNTIL RIGHT$(d2dividend$, 1) <> "0"
            d2dividend$ = MID$(d2dividend$, 1, LEN(d2dividend$) - 1) ' Strip off trailing zeros
        LOOP
        d2dividend$ = MID$(d2dividend$, 1, INSTR(d2dividend$, ".") - 1) + MID$(d2dividend$, INSTR(d2dividend$, ".") + 1) ' Strip off decimal point.
    ELSE
        d2dividend$ = d2dividend$ + STRING$(divplace&, "0") ' Add any zeros based on the length of dividend at decimal - length of divisor at decimal. If less than zero, nothing added.
        divplace& = 0
    END IF
    DO
        DO
            divremainder& = divremainder& + 1: divremainder$ = divremainder$ + MID$(d2dividend$, divremainder&, 1)
            IF MID$(d2dividend$, divremainder&, 1) = "" THEN
                IF divremainder$ = STRING$(LEN(divremainder$), "0") AND LEN(quotient$) > LEN(d2dividend$) THEN
                    divflag% = -1
                    terminating_decimal% = -1
                    EXIT DO
                END IF
                divcarry& = divcarry& + 1
                IF divcarry& = 1 THEN divplace3& = divremainder& - 1
                IF divcarry& > limit&& + 1 + divbuffer& THEN
                    divflag% = -2: EXIT DO
                END IF
                divremainder$ = divremainder$ + "0" ' No more digits to bring down.
            END IF
            IF LEN(divremainder$) > LEN(d1divisor$) OR LEN(divremainder$) = LEN(d1divisor$) AND divremainder$ >= d1divisor$ THEN EXIT DO
            quotient$ = quotient$ + "0"
        LOOP
        IF divflag% THEN divflag% = 0: EXIT DO
        FOR div_i% = 9 TO 1 STEP -1
            stringmatha$ = LTRIM$(STR$(div_i%)): stringmathb$ = d1divisor$
            m_product$ = "": GOSUB string_multiply_new
            tempcutd$ = divremainder$ ' divremainder$ can be 00 or other leading zero values.
            DO
                IF LEN(tempcutd$) = 1 THEN EXIT DO
                IF LEFT$(tempcutd$, 1) = "0" THEN
                    tempcutd$ = MID$(tempcutd$, 2)
                ELSE
                    EXIT DO
                END IF
            LOOP
            IF LEN(tempcutd$) > LEN(m_product$) OR LEN(tempcutd$) = LEN(m_product$) AND m_product$ <= tempcutd$ THEN EXIT FOR
        NEXT
        quotient$ = quotient$ + LTRIM$(STR$(div_i%))
        stringmatha$ = LTRIM$(STR$(div_i%)): stringmathb$ = d1divisor$
        m_product$ = "": GOSUB string_multiply_new
        operator$ = "-"
        stringmatha$ = divremainder$
        stringmathb$ = m_product$
        GOSUB string_add_subtract_new
        divremainder$ = stringmatha$
        operator$ = "/"
    LOOP
    IF divplace& = 0 AND divplace2& = 0 THEN divplace& = divplace3&
    IF divplace2& THEN divplace& = divplace& + divplace2& - 1
    IF quotient$ = "" THEN divplace& = 0 ' dividend is zero.
    IF divplace& OR divplace2& THEN
        quotient$ = MID$(quotient$, 1, divplace&) + "." + MID$(quotient$, divplace& + 1)
        DO UNTIL RIGHT$(quotient$, 1) <> "0"
            quotient$ = MID$(quotient$, 1, LEN(quotient$) - 1) ' Strip off trailing zeros
        LOOP
        IF RIGHT$(quotient$, 1) = "." THEN quotient$ = MID$(quotient$, 1, LEN(quotient$) - 1) ' Strip off abandoned decimal.
    END IF
    DO UNTIL LEFT$(quotient$, 1) <> "0"
        quotient$ = MID$(quotient$, 2) ' Strip off leading zeros
    LOOP
    IF quotient$ = "" THEN quotient$ = "0": divsign% = 0
    operationdivision% = 0
    stringmathb$ = quotient$: quotient$ = ""

    IF stringmathb$ = "overflow" THEN divsign% = 0: operationdivision% = 0: EXIT SUB

    runningtotal$ = stringmathb$: stringmathb$ = ""
    IF divsign% THEN runningtotal$ = "-" + runningtotal$

    IF stringmathround$ <> "" THEN runningtotal$ = runningtotal$ + stringmathround$
    operationdivision% = 0
    EXIT SUB

    '------------------------------------------------------------------------
    string_add_subtract_new:
    s = 18

    a$ = stringmatha$: b$ = stringmathb$: op$ = operator$

    IF op$ = "-" THEN
        IF LEFT$(b$, 1) = "-" THEN b$ = MID$(b$, 2) ELSE b$ = "-" + b$
    END IF

    IF INSTR(a$, ".") <> 0 OR INSTR(b$, ".") <> 0 THEN
        decimal% = -1
        IF INSTR(a$, ".") <> 0 THEN
            dec_a&& = LEN(MID$(a$, INSTR(a$, ".") + 1))
            a$ = MID$(a$, 1, INSTR(a$, ".") - 1) + MID$(a$, INSTR(a$, ".") + 1)
        END IF
        IF INSTR(b$, ".") <> 0 THEN
            dec_b&& = LEN(MID$(b$, INSTR(b$, ".") + 1))
            b$ = MID$(b$, 1, INSTR(b$, ".") - 1) + MID$(b$, INSTR(b$, ".") + 1)
        END IF
        ' Line up decimal places by inserting trailing zeros.
        IF dec_b&& > dec_a&& THEN
            j&& = dec_b&&
            a$ = a$ + STRING$(dec_b&& - dec_a&&, "0")
        ELSE
            j&& = dec_a&&
            b$ = b$ + STRING$(dec_a&& - dec_b&&, "0")
        END IF
    END IF

    IF LEFT$(a$, 1) = "-" OR LEFT$(b$, 1) = "-" THEN
        IF LEFT$(a$, 1) = "-" AND LEFT$(b$, 1) = "-" THEN
            sign$ = "--": a$ = MID$(a$, 2): b$ = MID$(b$, 2)
        ELSE
            IF LEFT$(a$, 1) = "-" THEN a$ = MID$(a$, 2): sign_a$ = "-"
            IF LEFT$(b$, 1) = "-" THEN b$ = MID$(b$, 2): sign_b$ = "-"

            IF LEFT$(a1$, 1) = "-" THEN a1_x$ = MID$(a1$, 2) ELSE a1_x$ = a1$
            IF LEFT$(b1$, 1) = "-" THEN b1_x$ = MID$(b1$, 2) ELSE b1_x$ = b1$

            string_compare a1_x$, b1_x$, gl%

            IF gl% < 0 THEN
                IF LEN(sign_b$) THEN sign$ = "-": SWAP a$, b$
            ELSE
                IF LEN(sign_a$) THEN sign$ = "-": SWAP sign_a$, sign_b$
            END IF
        END IF
    END IF

    s = 18: z$ = ""

    DO
        i&& = i&& + s
        x1$ = MID$(a$, LEN(a$) - i&& + 1, s)
        x2$ = MID$(b$, LEN(b$) - i&& + 1, s)
        a = VAL(sign_a$ + x1$) + VAL(sign_b$ + x2$) + c
        IF x1$ + x2$ = "" AND c = 0 THEN EXIT DO
        c = 0
        IF a > VAL(STRING$(s, "9")) THEN a = a - 10 ^ s: c = 1
        IF a < 0 THEN a = a + 10 ^ s: c = -1
        tmp$ = LTRIM$(STR$(a))
        z$ = STRING$(LEN(x1$) - LEN(tmp$), "0") + tmp$ + z$
    LOOP

    IF decimal% THEN
        z$ = MID$(z$, 1, LEN(z$) - j&&) + "." + MID$(z$, LEN(z$) - j&& + 1)
    END IF

    ' Remove any leading zeros.
    DO
        IF LEFT$(z$, 1) = "0" THEN z$ = MID$(z$, 2) ELSE EXIT DO
    LOOP

    IF z$ = "" OR z$ = "0" THEN z$ = "0" ELSE z$ = LEFT$(sign$, 1) + z$

    runningtotal$ = z$ '*'
    sign$ = "": sign_a$ = "": sign_b$ = "": i&& = 0: j&& = 0: decimal% = 0: c = 0
    EXIT SUB

    '------------------------------------------------------------------------
    string_multiply_new:
    z$ = "": sign$ = "": mult&& = 0: h&& = 0: i&& = 0: j&& = 0: c = 0: decimal% = 0
    zz$ = "": ii&& = 0: jj&& = 0
    s = 8: ss = 18

    a$ = stringmatha$: b$ = stringmathb$

    IF INSTR(a$, "-") <> 0 OR INSTR(b$, "-") <> 0 THEN
        IF INSTR(a$, "-") <> 0 AND INSTR(b$, "-") <> 0 THEN
            a$ = MID$(a$, 2): b$ = MID$(b$, 2)
        ELSE
            IF INSTR(a$, "-") <> 0 THEN a$ = MID$(a$, 2) ELSE b$ = MID$(b$, 2)
            sign$ = "-"
        END IF
    END IF

    IF INSTR(a$, ".") <> 0 OR INSTR(b$, ".") <> 0 THEN
        decimal% = -1
        IF INSTR(a$, ".") <> 0 THEN
            dec_a&& = LEN(MID$(a$, INSTR(a$, ".") + 1))
            a$ = MID$(a$, 1, INSTR(a$, ".") - 1) + MID$(a$, INSTR(a$, ".") + 1)
        END IF
        IF INSTR(b$, ".") <> 0 THEN
            dec_b&& = LEN(MID$(b$, INSTR(b$, ".") + 1))
            b$ = MID$(b$, 1, INSTR(b$, ".") - 1) + MID$(b$, INSTR(b$, ".") + 1)
        END IF
    END IF

    DO
        h&& = h&& + s: i&& = 0
        x2$ = MID$(b$, LEN(b$) - h&& + 1, s)
        WHILE -1
            i&& = i&& + s
            x1$ = MID$(a$, LEN(a$) - i&& + 1, s)
            a = VAL(sign_a$ + x1$) * VAL(sign_b$ + x2$) + c
            IF betatest% THEN PRINT "x1$ = "; x1$;: LOCATE , 20: PRINT "x2$ = "; x2$;: LOCATE , 35: PRINT VAL(x1$) * VAL(x2$) + c;: LOCATE , 55: PRINT "c = "; c;: LOCATE , 75: PRINT "val = "; a,
            c = 0
            tmp$ = LTRIM$(STR$(a))
            IF LEN(tmp$) > s THEN c = VAL(MID$(tmp$, 1, LEN(tmp$) - s)): tmp$ = MID$(tmp$, LEN(tmp$) - s + 1)
            z$ = STRING$(LEN(x1$) - LEN(tmp$), "0") + tmp$ + z$
            IF betatest% THEN LOCATE , 100: PRINT a;: LOCATE , 120: PRINT z$
            IF i&& >= LEN(a$) AND c = 0 THEN EXIT WHILE
        WEND

        jj&& = jj&& + 1

        IF jj&& > 1 THEN
            ii&& = 0: cc = 0
            aa$ = holdaa$
            bb$ = z$ + STRING$((jj&& - 1) * s, "0")
            IF betatest% THEN PRINT "aa$ "; aa$; " + bb$ "; z$;: COLOR 14, 0: PRINT STRING$(jj&& - 1, "0"); " = ";: COLOR 7, 0: SLEEP
            DO
                ii&& = ii&& + ss
                xx1$ = MID$(aa$, LEN(aa$) - ii&& + 1, ss)
                xx2$ = MID$(bb$, LEN(bb$) - ii&& + 1, ss)
                aa = VAL(xx1$) + VAL(xx2$) + cc
                IF xx1$ + xx2$ = "" AND cc = 0 THEN EXIT DO ' Prevents leading zeros.
                cc = 0
                IF aa > VAL(STRING$(ss, "9")) THEN aa = aa - 10 ^ ss: cc = 1
                tmp$ = LTRIM$(STR$(aa))
                zz$ = STRING$(LEN(xx1$) - LEN(tmp$), "0") + tmp$ + zz$
            LOOP

            DO WHILE LEFT$(zz$, 1) = "0"
                IF LEFT$(zz$, 1) = "0" THEN zz$ = MID$(zz$, 2)
            LOOP
            IF zz$ = "" THEN zz$ = "0"

            holdaa$ = zz$
            IF betatest% THEN COLOR 2, 0: PRINT holdaa$: COLOR 7, 0
        ELSE
            holdaa$ = z$ + STRING$(jj&& - 1, "0")
        END IF

        z$ = "": zz$ = ""

    LOOP UNTIL h&& >= LEN(b$)

    z$ = holdaa$

    IF decimal% THEN
        DO UNTIL LEN(z$) >= dec_a&& + dec_b&&
            z$ = "0" + z$
        LOOP

        z$ = MID$(z$, 0, LEN(z$) - (dec_a&& + dec_b&& - 1)) + "." + MID$(z$, LEN(z$) - (dec_a&& + dec_b&&) + 1)

        DO UNTIL RIGHT$(z$, 1) <> "0" AND RIGHT$(z$, 1) <> "."
            z$ = MID$(z$, 1, LEN(z$) - 1)
        LOOP
    END IF

    IF z$ = "" OR z$ = "0" THEN z$ = "0": ELSE z$ = sign$ + z$

    decimal% = 0: sign$ = ""

    runningtotal$ = z$

    EXIT SUB

    replace_decimal:
    IF addsubplace& THEN
        addsubx1$ = STRING$(addsubplace& - LEN(addsubx1$), "0") + addsubx1$
        addsubx1$ = MID$(addsubx1$, 1, LEN(addsubx1$) - addsubplace&) + "." + MID$(addsubx1$, LEN(addsubx1$) - addsubplace& + 1)
        DO UNTIL RIGHT$(addsubx1$, 1) <> "0" ' Remove trailing zeros in a decimal sum.
            addsubx1$ = MID$(addsubx1$, 1, LEN(addsubx1$) - 1)
            addsubplace& = addsubplace& - 1
        LOOP
        IF RIGHT$(addsubx1$, 1) = "." THEN addsubx1$ = MID$(addsubx1$, 1, LEN(addsubx1$) - 1) ' Number is now an integer.
    END IF
    RETURN

    string_comp:
    DO
        ' Remove trailing zeros after a decimal point.
        IF INSTR(acomp$, ".") THEN
            DO UNTIL RIGHT$(acomp$, 1) <> "0" AND RIGHT$(acomp$, 1) <> "." AND RIGHT$(acomp$, 1) <> "-"
                acomp$ = MID$(acomp$, 1, LEN(acomp$) - 1)
            LOOP
        END IF
        IF INSTR(bcomp$, ".") THEN
            DO UNTIL RIGHT$(bcomp$, 1) <> "0" AND RIGHT$(bcomp$, 1) <> "." AND RIGHT$(bcomp$, 1) <> "-"
                bcomp$ = MID$(bcomp$, 1, LEN(bcomp$) - 1)
            LOOP
        END IF

        IF MID$(acomp$, 1, 2) = "-0" OR acomp$ = "" OR acomp$ = "-" THEN acomp$ = "0"
        IF MID$(bcomp$, 1, 2) = "-0" OR bcomp$ = "" OR bcomp$ = "-" THEN bcomp$ = "0"

        ' A - and +
        IF LEFT$(acomp$, 1) = "-" THEN j% = -1
        IF LEFT$(bcomp$, 1) = "-" THEN k% = -1
        IF k% = 0 AND j% THEN gl% = -1: EXIT DO
        IF j% = 0 AND k% THEN gl% = 1: EXIT DO

        ' A decimal and non-decimal.
        j% = INSTR(acomp$, ".")
        k% = INSTR(bcomp$, ".")
        IF j% = 0 AND k% THEN
            IF acomp$ = "0" THEN gl% = -1 ELSE gl% = 1
            EXIT DO
        END IF
        IF k% = 0 AND j% THEN
            IF bcomp$ = "0" THEN gl% = 1 ELSE gl% = -1
            EXIT DO
        END IF

        ' Both decimals.
        IF j% THEN
            IF acomp$ > bcomp$ THEN
                gl% = 1
            ELSEIF acomp$ = bcomp$ THEN gl% = 0
            ELSEIF acomp$ < bcomp$ THEN gl% = -1
            END IF
            EXIT DO
        END IF

        ' Both positive or both negative whole numbers.
        SELECT CASE LEN(acomp$)
            CASE IS < LEN(bcomp$)
                gl% = -1
            CASE IS = LEN(bcomp$)
                IF acomp$ = bcomp$ THEN
                    gl% = 0
                ELSEIF acomp$ > bcomp$ THEN gl% = 1
                ELSEIF acomp$ < bcomp$ THEN gl% = -1
                END IF
            CASE IS > LEN(bcomp$)
                gl% = 1
        END SELECT
        EXIT DO
    LOOP
    RETURN
END SUB

SUB string_compare (compa$, compb$, gl%)
    DO
        ' Remove trailing zeros after a decimal point.
        IF INSTR(compa$, ".") THEN
            DO UNTIL RIGHT$(compa$, 1) <> "0" AND RIGHT$(compa$, 1) <> "." AND RIGHT$(compa$, 1) <> "-"
                compa$ = MID$(compa$, 1, LEN(compa$) - 1)
            LOOP
        END IF
        IF INSTR(compb$, ".") THEN
            DO UNTIL RIGHT$(compb$, 1) <> "0" AND RIGHT$(compb$, 1) <> "." AND RIGHT$(compb$, 1) <> "-"
                compb$ = MID$(compb$, 1, LEN(compb$) - 1)
            LOOP
        END IF

        IF MID$(compa$, 1, 2) = "-0" OR compa$ = "" OR compa$ = "-" THEN compa$ = "0"
        IF MID$(compb$, 1, 2) = "-0" OR compb$ = "" OR compb$ = "-" THEN compb$ = "0"

        ' A - and +
        IF LEFT$(compa$, 1) = "-" THEN j% = -1
        IF LEFT$(compb$, 1) = "-" THEN k% = -1
        IF k% = 0 AND j% THEN gl% = -1: PRINT "1*": EXIT DO
        IF j% = 0 AND k% THEN gl% = 1: PRINT "2*": EXIT DO

        ' A decimal and non-decimal.
        j% = INSTR(compa$, ".")
        k% = INSTR(compb$, ".")

        IF j% = 0 AND k% THEN
            IF compa$ = "0" THEN gl% = -1: PRINT "4*" ELSE gl% = 1: PRINT "5*"
            EXIT DO
        END IF
        IF k% = 0 AND j% THEN
            IF compb$ = "0" THEN gl% = 1: PRINT "6*" ELSE gl% = -1: PRINT "7*"
            EXIT DO
        END IF

        ' Both decimals.
        IF j% THEN
            IF compa$ > compb$ THEN
                gl% = 1: PRINT "8*"
            ELSEIF compa$ = compb$ THEN gl% = 0: PRINT "9*"
            ELSEIF compa$ < compb$ THEN gl% = -1: PRINT "10*"
            END IF
            EXIT DO
        END IF

        ' Both positive or both negative whole numbers.
        SELECT CASE LEN(compa$)
            CASE IS < LEN(compb$)
                gl% = -1
            CASE IS = LEN(compb$)
                IF compa$ = compb$ THEN
                    gl% = 0
                ELSEIF compa$ > compb$ THEN gl% = 1
                ELSEIF compa$ < compb$ THEN gl% = -1
                END IF
            CASE IS > LEN(compb$)
                gl% = 1
        END SELECT
        EXIT DO
    LOOP
END SUB

SUB validate_string (stringmathb$)
    DO ' Faux loop.
        vsn_negcnt& = 0: vsn_poscnt& = 0: vsn_depresent& = 0: decimalcnt& = 0: vsn_numberpresent& = 0: vsn_zerospresent& = 0
        IF LEFT$(stringmathb$, 1) = "-" THEN stringmathb$ = MID$(stringmathb$, 2): sm_sign$ = "-" ELSE sm_sign$ = ""
        IF LEFT$(stringmathb$, 1) = "+" THEN IF sm_sign$ <> "-" THEN stringmathb$ = MID$(stringmathb$, 2) ELSE stringmathb$ = "invalid number": EXIT DO
        IF INSTR(UCASE$(stringmathb$), "D") OR INSTR(UCASE$(stringmathb$), "E") THEN ' Evaluate for Scientific Notation.
            FOR sm_i& = 1 TO LEN(stringmathb$)
                validatenum$ = MID$(UCASE$(stringmathb$), sm_i&, 1)
                SELECT CASE validatenum$
                    CASE "+"
                        IF vsn_depresent& THEN vsn_poscnt& = vsn_poscnt& + 1 ELSE stringmathb$ = "invalid number": EXIT DO
                    CASE "-"
                        IF vsn_depresent& THEN vsn_negcnt& = vsn_negcnt& + 1 ELSE stringmathb$ = "invalid number": EXIT DO
                    CASE "0" TO "9"
                        vsn_numberpresent& = -1
                    CASE "D", "E"
                        vsn_depresent& = vsn_depresent& + 1
                        IF decimalcnt& = 0 AND sm_i& <> 2 OR vsn_depresent& > 1 OR vsn_numberpresent& = 0 OR vsn_negcnt& > 1 OR vsn_poscnt& > 1 OR vsn_negcnt& = 1 AND vsn_poscnt& >= 1 THEN vsn_numberpresent& = 0: EXIT FOR
                        vsn_numberpresent& = 0
                        MID$(stringmathb$, sm_i&, 1) = "e" ' Standardize
                    CASE "."
                        decimalcnt& = decimalcnt& + 1
                        IF sm_i& <> 2 THEN vsn_numberpresent& = 0: EXIT FOR
                    CASE ELSE
                        vsn_numberpresent& = 0: EXIT FOR
                END SELECT
            NEXT
            IF decimalcnt& = 0 THEN stringmathb$ = MID$(stringmathb$, 1, 1) + "." + MID$(stringmathb$, 2) ' Standardize "."
            IF vsn_numberpresent& = 0 OR vsn_negcnt& = 1 AND vsn_poscnt& = 1 OR decimalcnt& > 1 OR INSTR(stringmathb$, ".") <> 2 THEN stringmathb$ = "invalid number": EXIT DO
            vsn_depresent& = INSTR(stringmathb$, "e")
            sm_x$ = MID$(stringmathb$, vsn_depresent& + 1, 1) ' Standardize exponent "+" these two lines.
            IF sm_x$ <> "+" AND sm_x$ <> "-" THEN stringmathb$ = MID$(stringmathb$, 1, vsn_depresent&) + "+" + MID$(stringmathb$, vsn_depresent& + 1)
            IF MID$(stringmathb$, vsn_depresent& + 2, 1) = "0" THEN
                IF MID$(stringmathb$, vsn_depresent& + 3, 1) <> "" THEN stringmathb$ = "invalid number": EXIT DO ' No leading zeros allowed in exponent notation.
            END IF
            jjed& = INSTR(stringmathb$, "e") ' Get position of notation.
            valexpside$ = MID$(stringmathb$, jjed&) ' These two lines break up into number and notation
            stringmathb$ = MID$(stringmathb$, 1, jjed& - 1) ' stringmathb$ is +- single digit whole number, decimal point and decimal number. valexpside$ is notation, sign and exponent.
            DO UNTIL RIGHT$(stringmathb$, 1) <> "0" ' Remove any trailing zeros for number. Example 1.0d3 or 1.0000d3, etc.
                stringmathb$ = MID$(stringmathb$, 1, LEN(stringmathb$) - 1)
            LOOP
            IF VAL(MID$(stringmathb$, 1, INSTR(stringmathb$, ".") - 1)) = 0 THEN
                IF RIGHT$(stringmathb$, 1) = "." THEN
                    stringmathb$ = "0.e+0" ' Handles all types of zero entries.
                ELSE
                    stringmathb$ = "invalid number": EXIT DO
                END IF
                EXIT DO
            END IF
            stringmathb$ = sm_sign$ + stringmathb$ + valexpside$
            EXIT DO
        ELSE
            FOR sm_i& = 1 TO LEN(stringmathb$)
                validatenum$ = MID$(stringmathb$, sm_i&, 1)
                SELECT CASE validatenum$
                    CASE "."
                        decimalcnt& = decimalcnt& + 1
                    CASE "0"
                        vsn_zerospresent& = -1
                    CASE "1" TO "9"
                        vsn_numberpresent& = -1
                    CASE "$"
                    CASE ELSE
                        stringmathb$ = "invalid number": EXIT DO
                END SELECT
            NEXT
            IF decimalcnt& > 1 OR vsn_negcnt& > 1 OR vsn_poscnt& > 1 OR vsn_negcnt& >= 1 AND vsn_poscnt& >= 1 THEN
                stringmathb$ = "invalid number": EXIT DO
            END IF

            REM IF INSTR(stringmathb$, "$") THEN GOSUB currency_validate
            REM IF INSTR(stringmathb$, ",") THEN
            REM GOSUB comma_validation
            REM IF stringmathb$ = "invalid number" THEN exit do
            REM GOSUB comma_removal
            REM END IF

            IF RIGHT$(stringmathb$, 1) = "." THEN stringmathb$ = MID$(stringmathb$, 1, LEN(stringmathb$) - 1)
            DO UNTIL LEFT$(stringmathb$, 1) <> "0" ' Strip off any leading zeros.
                stringmathb$ = MID$(stringmathb$, 2)
            LOOP
            stringmathb$ = sm_sign$ + stringmathb$
            IF INSTR(stringmathb$, ".") THEN
                DO UNTIL RIGHT$(stringmathb$, 1) <> "0" ' Strip off any trailing zeros in a decimal.
                    stringmathb$ = MID$(stringmathb$, 1, LEN(stringmathb$) - 1)
                LOOP
            END IF
            IF RIGHT$(stringmathb$, 1) = "." THEN stringmathb$ = MID$(stringmathb$, 1, LEN(stringmathb$) - 1)
            IF vsn_numberpresent& = 0 THEN
                IF vsn_zerospresent& THEN
                    stringmathb$ = "0"
                ELSE
                    stringmathb$ = "invalid number"
                END IF
            END IF
        END IF
        EXIT DO
    LOOP
END SUB


Pete
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