QB64 Phoenix Edition
Don't make me REPETEND myself... - Printable Version

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+--- Thread: Don't make me REPETEND myself... (/showthread.php?tid=706)

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RE: Don't make me REPETEND myself... - Dav - 08-03-2022

Hey @Stuart, the extra spaces happens to me too.  You can edit them out by clicking on the 'View Source' icon just above the editing window on the top left next to the Maximize icon (go into 'Full edit' mode first, not the 'Quick Edit' one).  You can also press Ctrl+Shift+S to enter it.  After selecting that you can do some 'true' editing.   I have to use it all the time to remove those extra spaces in my edited posts.







- Dav


RE: Don't make me REPETEND myself... - Pete - 08-03-2022

@Stuart

Great post! Woohoo, my routine was able to identify .000000000000001184237892933500309785207112630208333333 as an eventual infinite repetend of 3s.

.000000000000001184237892933500309785207112630208333333

So for fun, let's turn that decimal into a fraction...

10^48 * .000000000000001184237892933500309785207112630208333333 = 1184237892933500309785207112630208.333333
10^ 50 * .000000000000001184237892933500309785207112630208333333 = 118423789293350030978520711263020833.3333

118423789293350030978520711263020833.333333
- 1184237892933500309785207112630208.333333
------------------------------------------------------------
117239551400416530668735504150390625

99000000000000000000000000000000000000000000000000 / 117239551400416530668735504150390625 =

1 / 844424930131968

I bring this up because since I'm not onboard with resorting to bit turning math, or whatever it's called, I'm getting curious about converting to fractions to round repetends. As such...

1 / 3 * 3

digital = 1 / 3 = .3... but * 3 = .999... unless the repetend is handled properly in multiplying back to 1.

So with fractions,

1 3
- * - = 1 No problem.
3 1

so if I write an algorithm that does the following...

.3... * 3

10x * .3... = 3.3...
1000x * .3 = 333.3
333.3
- 3.3 = 330
1000x
- 10x = 990x
990x = 330
330 / 990 reduced = 1 /3
1 / 3 * 3 = 3 /3 = 1
So converting to fraction multiplication now 1 / 3 * 3 = 1 instead of .9...

Well, easy in theory, but when we get into really big number repetends, it might be difficult and slow to implement.

Pete


RE: Don't make me REPETEND myself... - Pete - 08-03-2022

Here's a nice little routine I coded using the Euclidean algorithm to determine the GCF and then reducing the fraction. The example uses that big eventual repeating decimal in the last post: .000000000000001184237892933500309785207112630208333333... While the numerator in this example reduces to 1 and only requires 1 loop to calculate, you can remove the REM statements to test something a bit more complicated that takes 4 loops to calculate.

Code: (Select All)
WIDTH 166, 25
_SCREENMOVE 0, 0
a$ = "117239551400416530668735504150390625"
b$ = "99000000000000000000000000000000000000000000000000"
REM a$ = "156"
REM b$ = "388"
gfca$ = a$: gfcb$ = b$

IF VAL(gfca$) < VAL(gfcb$) THEN SWAP gfca$, gfcb$

DO
    i = i + 1
    x = VAL(gfca$) MOD VAL(gfcb$)
    SWAP gfca$, gfcb$: gfcb$ = LTRIM$(STR$(x))
    IF x = 0 THEN EXIT DO
LOOP
PRINT "Loops:"; i; " ";
PRINT a$; "/"; b$; "  ";
PRINT "GFC = "; gfca$; "  ";
PRINT LTRIM$(STR$(VAL(a$) / VAL(gfca$))) + "/" + LTRIM$(STR$(VAL(b$) / VAL(gfca$)))



RE: Don't make me REPETEND myself... - Pete - 08-03-2022

So next up is a way to convert decimals to fractions. This is a test but if it works in all cases, it would be easy to set it up as a conversion calculator. Of course for now, I've left out the string math, so it is limited to around a dozen digits before VAL() craps out. That won't be a problem once it is plugged into the string math routine, later...

Code: (Select All)
repetend_class$ = "mixed"
n$ = ".076923076923" ' 1/13th.

IF repetend_class$ = "single" THEN
    ' Infinite repeating of one digit...
    ' Loop until the first digit after the decimal is non-zero: i%
    i% = 0
    DO
        i% = i% + 1
        x$ = MID$(n$, 1 + i%, 1)
        IF VAL(x$) THEN EXIT DO
        IF i% = LEN(n$) THEN BEEP: EXIT DO ' Error all zeros.
    LOOP
    a$ = LTRIM$(STR$(INT(VAL(n$) * 10 ^ (i% + 1)) - INT(VAL(n$) * 10 ^ i%)))
    b$ = LTRIM$(STR$(10 ^ (i% + 1) - 10 ^ i%))
ELSE
    ' Infinite repeating of two or more digits...
    i% = 0
    DO
        i% = i% + 1
        x$ = MID$(n$, 1 + i%, 1)
        IF VAL(x$) THEN EXIT DO
        IF i% = LEN(n$) THEN BEEP: EXIT DO ' Error all zeros.
    LOOP
    a$ = LTRIM$(STR$(VAL(MID$(n$ + MID$(n$, 2), 2, LEN(n$) - 1 + i%)) - VAL(MID$(n$, 2, i%))))
    b$ = LTRIM$(STR$(10 ^ (LEN(n$) - 1 + i%) - 10 ^ i%))
END IF

' GFC algorithm. -------------------------------------------------------------

gfca$ = a$: gfcb$ = b$

IF VAL(gfca$) < VAL(gfcb$) THEN SWAP gfca$, gfcb$

DO
    i = i + 1
    x = VAL(gfca$) MOD VAL(gfcb$)
    SWAP gfca$, gfcb$: gfcb$ = LTRIM$(STR$(x))
    IF x = 0 THEN EXIT DO
LOOP
PRINT "Decimal: "; n$
PRINT "Loops:"; i; " "
PRINT "Conversion: "; a$; " / "; b$; "  "
PRINT "GFC = "; gfca$; "  "
PRINT "Fraction: "; LTRIM$(STR$(VAL(a$) / VAL(gfca$))) + "/" + LTRIM$(STR$(VAL(b$) / VAL(gfca$)))
END



RE: Don't make me REPETEND myself... - Stuart - 08-04-2022

(08-03-2022, 10:37 AM)Dav Wrote: Hey @Stuart, the extra spaces happens to me too.  You can edit them out by clicking on the 'View Source' icon just above the editing window on the top left next to the Maximize icon (go into 'Full edit' mode first, not the 'Quick Edit' one).  You can also press Ctrl+Shift+S to enter it.  After selecting that you can do some 'true' editing.   I have to use it all the time to remove those extra spaces in my edited posts.

- Dav

Thank you very much for the info about posting and editing; my original post looks so much better now.


RE: Don't make me REPETEND myself... - Pete - 08-04-2022

Okay, this is how we do decimals to fractions in string math...

Code: (Select All)
'repetend_class$ = "mixed"
'n$ = ".076923076923" ' 1/13th.

'repetend_class$ = "single"
'n$ = ".1111" ' 1/9th.

repetend_class$ = "mixed"
n$ = ".052631578947368421" ' 1/19th.

IF repetend_class$ = "single" THEN
    ' Infinite repeating of one digit...
    ' Loop until the first digit after the decimal is non-zero: i%
    ii% = 0
    DO
        ii% = ii% + 1
        x$ = MID$(n$, 1 + ii%, 1)
        IF x$ <> "0" THEN EXIT DO
        IF ii% = LEN(n$) THEN BEEP: EXIT DO ' Error all zeros.
    LOOP

    a$ = LTRIM$(STR$(INT(VAL(n$) * 10 ^ (ii% + 1)) - INT(VAL(n$) * 10 ^ ii%)))

    runningtotal$ = "1"
    FOR j = 1 TO ii% + 1
        stringmatha$ = runningtotal$: stringmathb$ = "10"
        operator$ = "*": GOSUB string_multiply
    NEXT
    stringmatha$ = runningtotal$
    stringmathb$ = n$
    operator$ = "*": GOSUB string_multiply
    m1$ = MID$(runningtotal$, 1, INSTR(runningtotal$, ".") - 1)

    runningtotal$ = "1"
    FOR j = 1 TO ii%
        stringmatha$ = runningtotal$: stringmathb$ = "10"
        operator$ = "*": GOSUB string_multiply
    NEXT
    stringmatha$ = runningtotal$
    stringmathb$ = n$
    operator$ = "*": GOSUB string_multiply
    m2$ = MID$(runningtotal$, 1, INSTR(runningtotal$, ".") - 1)
    stringmatha$ = m1$: stringmathb$ = m2$
    operator$ = "-": GOSUB string_add_subtract
    a$ = runningtotal$

    runningtotal$ = "1"
    FOR j = 1 TO ii%
        stringmatha$ = runningtotal$: stringmathb$ = "10"
        operator$ = "*": GOSUB string_multiply
    NEXT
    stringmatha$ = m1$: stringmathb$ = runningtotal$

    runningtotal$ = "1"
    FOR j = 1 TO ii% + 1
        stringmatha$ = runningtotal$: stringmathb$ = "10"
        operator$ = "*": GOSUB string_multiply
    NEXT
    m1$ = runningtotal$
    runningtotal$ = "1"
    FOR j = 1 TO ii%
        stringmatha$ = runningtotal$: stringmathb$ = "10"
        operator$ = "*": GOSUB string_multiply
    NEXT
    stringmatha$ = m1$: stringmathb$ = runningtotal$
    operator$ = "-": GOSUB string_add_subtract
    b$ = runningtotal$
ELSE
    ' Infinite repeating of two or more digits...
    ii% = 0
    DO
        ii% = ii% + 1
        x$ = MID$(n$, 1 + ii%, 1)
        IF x$ <> "0" THEN EXIT DO
        IF ii% = LEN(n$) THEN BEEP: EXIT DO ' Error all zeros.
    LOOP

    stringmatha$ = MID$(n$ + MID$(n$, 2), 2, LEN(n$) - 1 + ii%)
    stringmathb$ = MID$(n$, 2, ii%)
    operator$ = "-": GOSUB string_add_subtract
    a$ = runningtotal$

    runningtotal$ = "1"
    FOR j = 1 TO LEN(n$) - 1 + ii%
        stringmatha$ = runningtotal$: stringmathb$ = "10"
        operator$ = "*": GOSUB string_multiply
    NEXT
    m1$ = runningtotal$

    runningtotal$ = "1"
    FOR j = 1 TO ii%
        stringmatha$ = runningtotal$: stringmathb$ = "10"
        operator$ = "*": GOSUB string_multiply
    NEXT
    stringmatha$ = m1$: stringmathb$ = runningtotal$
    operator$ = "-": GOSUB string_add_subtract
    b$ = runningtotal$
END IF

' GFC algorithm. -------------------------------------------------------------

gfca$ = a$: gfcb$ = b$

IF VAL(gfca$) < VAL(gfcb$) THEN SWAP gfca$, gfcb$

i = 0
DO
    i = i + 1
    ' MOD operation in string math.
    stringmatha$ = gfca$: stringmathb$ = gfcb$
    operator$ = "/": GOSUB string_divide
    m1$ = runningtotal$
    IF INSTR(m1$, ".") THEN m1$ = MID$(m1$, 1, INSTR(m1$, ".") - 1)
    stringmatha$ = m1$
    stringmathb$ = gfcb$
    operator$ = "*": GOSUB string_multiply
    m2$ = runningtotal$

    stringmatha$ = gfca$: stringmathb$ = m2$
    operator$ = "-": GOSUB string_add_subtract
    SWAP gfca$, gfcb$: gfcb$ = runningtotal$
    IF runningtotal$ = "0" THEN EXIT DO
LOOP

stringmatha$ = a$: stringmathb$ = gfca$
operator$ = "/": GOSUB string_divide
numerator$ = runningtotal$
stringmatha$ = b$: stringmathb$ = gfca$
operator$ = "/": GOSUB string_divide
denominator$ = runningtotal$

PRINT "Decimal: "; n$
PRINT "Loops:"; i; " "
PRINT "Conversion: "; a$; " / "; b$; "  "
PRINT "GFC = "; gfca$; "  "
PRINT "Fraction: "; numerator$ + " / " + denominator$
END

a$ = "117239551400416530668735504150390625"
b$ = "99000000000000000000000000000000000000000000000000"
REM a$ = "156"
REM b$ = "388"
a$ = "1428570"
b$ = "9999990"
a$ = "11109"
b$ = "90000"

PRINT i%,
PRINT 10 ^ i%,
PRINT 10 ^ (i% + 1)
PRINT INT(VAL(n$) * 10 ^ (i% + 1)),
PRINT INT(VAL(n$) * 10 ^ i%),
PRINT INT(VAL(n$) * 10 ^ (i% + 1)) - INT(VAL(n$) * 10 ^ i%),
PRINT 10 ^ (i% + 1) - 10 ^ i%

string_divide:
divremainder& = 0: divremainder$ = "": divplace& = 0 AND 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$) = 1 THEN PRINT "Division by zero not allowed.": divsign% = 0: operationdivision% = 0: RETURN '*'
IF LEFT$(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: EXIT DO
            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$: quotient$ = ""
'''GOSUB limit_round_convert
IF stringmathb$ = "overflow" THEN divsign% = 0: operationdivision% = 0: RETURN '*'
'''GOSUB sm_converter
runningtotal$ = stringmathb$: stringmathb$ = ""
IF divsign% THEN runningtotal$ = "-" + runningtotal$

IF stringmathround$ <> "" THEN runningtotal$ = runningtotal$ + stringmathround$
operationdivision% = 0 '''''
RETURN '*'

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$) TO 1 STEP -1 ' Multiply each charter top and bottom.
    m_k& = m_l&
    m_x2$ = 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$: m_product$ = ""
'''GOSUB limit_round_convert
IF stringmathb$ = "overflow" THEN RETURN '*'
'''GOSUB sm_converter
runningtotal$ = stringmathb$: stringmathb$ = ""
IF m_sign% THEN runningtotal$ = "-" + runningtotal$: m_sign% = 0
RETURN

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)
        IF VAL(stringmathb$) > VAL(stringmatha$) 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)
        IF VAL(stringmathb$) > VAL(stringmatha$) THEN SWAP stringmatha$, stringmathb$ ELSE 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
''' GOSUB limit_round_convert
IF stringmathb$ = "overflow" THEN n2sign$ = "": RETURN '*'
''' GOSUB sm_converter
runningtotal$ = n2sign$ + stringmathb$: n2sign$ = ""
RETURN

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

So now it can handle very long periodic decimals and convert them. I just need to double check on using VAL() for swapping. I may need to replace that with a string routine, too.

Pete


RE: Don't make me REPETEND myself... - Jack - 08-04-2022

Pete
for single character it may be faster to do Asc(n$)-48 rather than using Val
also, if you use Val in conjunction with Mid$ to get the value of a character then you can forgo the Mid$ function and use Asc(n$, index)-48


RE: Don't make me REPETEND myself... - Stuart - 08-04-2022

(08-03-2022, 05:39 PM)Pete Wrote: @Stuart

Great post! Woohoo, my routine was able to identify .000000000000001184237892933500309785207112630208333333 as an eventual infinite repetend of 3s.

.000000000000001184237892933500309785207112630208333333

So for fun, let's turn that decimal into a fraction...

To be honest, at first I started getting a little lost at this point... but I eventually got it.

I'm glad you found the info interesting and useful.


Quote:So next up is a way to convert decimals to fractions. This is a test but if it works in all cases, it would be easy to set it up as a conversion calculator. Of course for now, I've left out the string math, so it is limited to around a dozen digits before VAL() craps out. That won't be a problem once it is plugged into the string math routine, later...

This works unless there are "unique digits" before the repetend begins.
Here's some info I found about converting repeating decimals to fractions even when there are "unique digits" : 

https://www.basic-mathematics.com/converting-repeating-decimals-to-fractions.html

(See Example #2)


RE: Don't make me REPETEND myself... - bplus - 08-04-2022

Function convert2Fraction$ (decimal$)
Function convertRnotation2Fraction$ (rNotedDecimal$)
Function gcd&& (a&&, b&&)

All outlined for integers in post #2, just use String math routines for extended precision..


RE: Don't make me REPETEND myself... - Pete - 08-04-2022

Fraction to decimal for terminating and non-terminating decimals. For this demo, you'll have to input a repeating mixed decimal like: .142857 would have to be input as: .142857142857. Single repeating like .33333 can be input with at least two digits like: .33


@Stuart Yes, I checked and although the other app I wrote recognizes your leading unique digits repetend, the decimal to fraction does not convert it properly. So the next update I will tweak the routine and hopefully be able to include unique digits in the conversion routine.

For now...

Code: (Select All)
LINE INPUT "Decimal: "; n$

GOSUB get_repetend_class

SELECT CASE repetend_class$
    CASE "null" ' Terminating decimals.
        runningtotal$ = "1"
        FOR j = 1 TO LEN(n$)
            stringmatha$ = runningtotal$: stringmathb$ = "10"
            operator$ = "*": GOSUB string_multiply
        NEXT
        m2$ = runningtotal$

        stringmatha$ = runningtotal$
        stringmathb$ = n$
        operator$ = "*": GOSUB string_multiply
        m1$ = runningtotal$
        a$ = m1$: b$ = m2$

    CASE "single"
        ' Infinite repeating of one digit...
        ' Loop until the first digit after the decimal is non-zero: i%
        ii% = 0
        DO
            ii% = ii% + 1
            x$ = MID$(n$, 1 + ii%, 1)
            IF x$ <> "0" THEN EXIT DO
            IF ii% = LEN(n$) THEN BEEP: EXIT DO ' Error all zeros.
        LOOP

        runningtotal$ = "1"
        FOR j = 1 TO ii% + 1
            stringmatha$ = runningtotal$: stringmathb$ = "10"
            operator$ = "*": GOSUB string_multiply
        NEXT
        stringmatha$ = runningtotal$
        stringmathb$ = n$
        operator$ = "*": GOSUB string_multiply
        m1$ = MID$(runningtotal$, 1, INSTR(runningtotal$, ".") - 1)

        runningtotal$ = "1"
        FOR j = 1 TO ii%
            stringmatha$ = runningtotal$: stringmathb$ = "10"
            operator$ = "*": GOSUB string_multiply
        NEXT
        stringmatha$ = runningtotal$
        stringmathb$ = n$
        operator$ = "*": GOSUB string_multiply
        m2$ = MID$(runningtotal$, 1, INSTR(runningtotal$, ".") - 1)
        stringmatha$ = m1$: stringmathb$ = m2$
        operator$ = "-": GOSUB string_add_subtract
        a$ = runningtotal$

        runningtotal$ = "1"
        FOR j = 1 TO ii%
            stringmatha$ = runningtotal$: stringmathb$ = "10"
            operator$ = "*": GOSUB string_multiply
        NEXT
        stringmatha$ = m1$: stringmathb$ = runningtotal$

        runningtotal$ = "1"
        FOR j = 1 TO ii% + 1
            stringmatha$ = runningtotal$: stringmathb$ = "10"
            operator$ = "*": GOSUB string_multiply
        NEXT
        m1$ = runningtotal$
        runningtotal$ = "1"
        FOR j = 1 TO ii%
            stringmatha$ = runningtotal$: stringmathb$ = "10"
            operator$ = "*": GOSUB string_multiply
        NEXT
        stringmatha$ = m1$: stringmathb$ = runningtotal$
        operator$ = "-": GOSUB string_add_subtract
        b$ = runningtotal$
    CASE ELSE ' Mixed.
        ' Infinite repeating of two or more digits...
        ii% = 0
        DO
            ii% = ii% + 1
            x$ = MID$(n$, 1 + ii%, 1)
            IF x$ <> "0" THEN EXIT DO
            IF ii% = LEN(n$) THEN BEEP: EXIT DO ' Error all zeros.
        LOOP

        stringmatha$ = MID$(n$ + MID$(n$, 2), 2, LEN(n$) - 1 + ii%)
        stringmathb$ = MID$(n$, 2, ii%)
        operator$ = "-": GOSUB string_add_subtract
        a$ = runningtotal$

        runningtotal$ = "1"
        FOR j = 1 TO LEN(n$) - 1 + ii%
            stringmatha$ = runningtotal$: stringmathb$ = "10"
            operator$ = "*": GOSUB string_multiply
        NEXT
        m1$ = runningtotal$

        runningtotal$ = "1"
        FOR j = 1 TO ii%
            stringmatha$ = runningtotal$: stringmathb$ = "10"
            operator$ = "*": GOSUB string_multiply
        NEXT
        stringmatha$ = m1$: stringmathb$ = runningtotal$
        operator$ = "-": GOSUB string_add_subtract
        b$ = runningtotal$
END SELECT

' GFC algorithm. -------------------------------------------------------------

gfca$ = a$: gfcb$ = b$

IF VAL(gfca$) < VAL(gfcb$) THEN SWAP gfca$, gfcb$

i = 0
DO
    i = i + 1
    ' MOD operation in string math.
    stringmatha$ = gfca$: stringmathb$ = gfcb$
    operator$ = "/": GOSUB string_divide
    m1$ = runningtotal$
    IF INSTR(m1$, ".") THEN m1$ = MID$(m1$, 1, INSTR(m1$, ".") - 1)
    stringmatha$ = m1$
    stringmathb$ = gfcb$
    operator$ = "*": GOSUB string_multiply
    m2$ = runningtotal$

    stringmatha$ = gfca$: stringmathb$ = m2$
    operator$ = "-": GOSUB string_add_subtract
    SWAP gfca$, gfcb$: gfcb$ = runningtotal$
    IF runningtotal$ = "0" THEN EXIT DO
LOOP

stringmatha$ = a$: stringmathb$ = gfca$
operator$ = "/": GOSUB string_divide
numerator$ = runningtotal$
stringmatha$ = b$: stringmathb$ = gfca$
operator$ = "/": GOSUB string_divide
denominator$ = runningtotal$

PRINT "Decimal: "; n$
PRINT "Loops:"; i; " "
PRINT "Conversion: "; a$; " / "; b$; "  "
PRINT "GFC = "; gfca$; "  "
PRINT "Fraction: "; numerator$ + " / " + denominator$
END

get_repetend_class:
x$ = MID$(n$, INSTR(n$, ".") + 1)
i = 1: j = 0: k = 0: repetend_class$ = ""
DO
    j = j + 1: k = k + 1
    z$ = MID$(x$, i, j)
    mp% = INSTR(LEN(z$) + i, x$, z$)
    REM COLOR 14, 0: PRINT z$, "i ="; i; "Len ="; LEN(z$); "Prog ="; i + LEN(z$); "mp% ="; mp%; "case ="; p; x$: COLOR 7, 0: SLEEP
    IF VAL(z$) AND mp% = LEN(z$) + i THEN
        FOR k = 0 TO LEN(MID$(x$, i)) / LEN(z$) - 1
            IF MID$(x$, i + k * LEN(z$), LEN(z$)) <> z$ THEN mp% = -1: EXIT FOR
        NEXT

        IF mp% > 0 THEN
            SELECT CASE LEN(z$)
                CASE 1
                    IF i = 1 THEN
                        msg$ = "Repetend infinite: " + STRING$(3, z$) + "..."
                        repetend$ = STRING$(3, z$)
                        repetend_class$ = "single"
                    ELSE
                        msg$ = "Repetend eventually infinite: " + STRING$(3, z$) + "..."
                        repetend$ = STRING$(3, z$)
                        repetend_class$ = "single"
                    END IF
                CASE ELSE
                    msg$ = "Repetend " + z$ + " " + "length = " + LTRIM$(STR$(LEN(z$)))
                    repetend$ = z$
            END SELECT
            EXIT DO
        END IF
    END IF
    IF LEN(z$) >= LEN(x$) - i + 1 / 2 THEN
        msg$ = "Non-repetend."
        repetend_class$ = "null"
        EXIT DO
    END IF
    IF mp% = 0 THEN j = 0: i = i + 1
LOOP
PRINT msg$: PRINT
i = 0: j = 0: k = 0: mp% = 0: z$ = "": msg$ = ""
RETURN

' String math routines. ------------------------------------------------------
string_divide:
divremainder& = 0: divremainder$ = "": divplace& = 0 AND 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$) = 1 THEN PRINT "Division by zero not allowed.": divsign% = 0: operationdivision% = 0: RETURN '*'
IF LEFT$(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: EXIT DO
            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$: quotient$ = ""
'''GOSUB limit_round_convert
IF stringmathb$ = "overflow" THEN divsign% = 0: operationdivision% = 0: RETURN '*'
'''GOSUB sm_converter
runningtotal$ = stringmathb$: stringmathb$ = ""
IF divsign% THEN runningtotal$ = "-" + runningtotal$

IF stringmathround$ <> "" THEN runningtotal$ = runningtotal$ + stringmathround$
operationdivision% = 0 '''''
RETURN '*'

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$) TO 1 STEP -1 ' Multiply each charter top and bottom.
    m_k& = m_l&
    m_x2$ = 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$: m_product$ = ""
'''GOSUB limit_round_convert
IF stringmathb$ = "overflow" THEN RETURN '*'
'''GOSUB sm_converter
runningtotal$ = stringmathb$: stringmathb$ = ""
IF m_sign% THEN runningtotal$ = "-" + runningtotal$: m_sign% = 0
RETURN

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)
        IF VAL(stringmathb$) > VAL(stringmatha$) 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)
        IF VAL(stringmathb$) > VAL(stringmatha$) THEN SWAP stringmatha$, stringmathb$ ELSE 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
''' GOSUB limit_round_convert
IF stringmathb$ = "overflow" THEN n2sign$ = "": RETURN '*'
''' GOSUB sm_converter
runningtotal$ = n2sign$ + stringmathb$: n2sign$ = ""
RETURN

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

@Jack Thanks for the alternative ASC() suggestion. I've used this statement for years for a variety of things but was not aware of the optional indexing. Always nice to learn something along the way. Thanks!

As for VAL(), I intend to update this little project and weed VAL out as much as possible unless VAL() or ASC() will only have limited digits within the bounds of the default datatype for those statements.

Pete