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+---- Thread: Math Function Plot (/showthread.php?tid=260)
Math Function Plot - dcromley - 04-28-2022
Working (playing) with the "PSET hat" program, I wanted to see some math functions. So another QB64 program was needed.
I know there are online function plotting and other QBPE programs, but I like simplicity, and I like my own. So here is what I use for plotting functions. Since you have to compile it to put in your functions, I put in comments to document the use of it. I hope it is clear. This version has a variety of functions for demonstration. I reserve the right to edit this to later versions.
Code: (Select All)
_Title "FunctionPlot" ' V1.0 dcromley 2022
Option _Explicit
DefSng A-Z: DefInt I-N: DefStr S
Screen _NewImage(1000, 750, 256)
Cls 0, 15: Color 0, 15
Dim Shared ulo, uhi, vlo, vhi, xlo, xhi, ylo, yhi
Dim Shared u, v, x, y, c, nfunc, xold, yold
ulo = 10: uhi = 989: vlo = 739: vhi = 10 ' screen limits
xyinit -8, 8, 1, -6, 6, 1 ' xlo xhi xdel; ylo yhi ydel =#= world limits
' the above line means x from -8 to +8 and grid lines every 1; 0 would be no grid lines
For nfunc = 1 To 9
c = 0 ' default color
For u = ulo To uhi: x = zxu(u) ' x
If nfunc = 1 Then y = 1 - x ^ 2 / 2
If nfunc = 2 Then y = Cos(x)
If nfunc = 3 Then c = 2: y = Sin(x)
If nfunc = 4 Then GoTo continue1 ' skip
If nfunc = 5 Then y = func5(x)
If nfunc = 6 Then y = func6(x, 1)
If nfunc = 7 Then GoTo continue1
If nfunc = 8 Then GoTo continue1
If nfunc = 9 Then GoTo continue1
If u > ulo Then zline xold, yold, x, y, c ' the plot lines
xold = x: yold = y
continue1:
Next u
Next nfunc
zSystem ' end
Function func5 (x) '
If x < 0 Then func5 = 0: Exit Function
c = 1 ' blue
Dim t: t = Sqr(x)
func5 = Sqr(x) ' Sin(t) + .4 * Sin(3 * x)
End Function
Function func6 (x, N) ' 2 options in this function
c = 4 ' red
If N = 1 Then func6 = 8 * (1 / 2 * Cos(x) - 1 / 7 * Cos(3 * x) + 1 / 8 * Cos(5 * x))
If N = 2 Then func6 = 8 * (.5 * Cos(x) - .125 * Cos(3 * x) + .07 * Cos(5 * x))
End Function
Sub xyinit (xxlo, xxhi, xdel, yylo, yyhi, ydel)
xlo = xxlo: xhi = xxhi: ylo = yylo: yhi = yyhi ' save to globals
If xdel > 0 Then ' vertial grid lines
zline 0, ylo, 0, yhi, c ' y axis
For x = xdel To zMax(Abs(xlo), Abs(xhi)) Step xdel ' other
If zBetween(x, xlo, xhi) Then zline x, ylo, x, yhi, 7
If zBetween(-x, xlo, xhi) Then zline -x, ylo, -x, yhi, 7
Next x
End If
If ydel > 0 Then ' horizontal grid lines
zline xlo, 0, xhi, 0, c ' x axis
For y = ydel To zMax(Abs(ylo), Abs(yhi)) Step ydel ' other
If zBetween(y, ylo, yhi) Then zline xlo, y, xhi, y, 7
If zBetween(-y, ylo, yhi) Then zline xlo, -y, xhi, -y, 7
Next y
End If
End Sub
Sub zline (x1, y1, x2, y2, c)
Line (zux(x1), zvy(y1))-(zux(x2), zvy(y2)), c
End Sub
Function zux (x)
zux = zLerplh(ulo, uhi, x, xlo, xhi)
End Function
Function zvy (y)
zvy = zLerplh(vlo, vhi, y, ylo, yhi)
End Function
Function zxu (u)
zxu = zLerplh(xlo, xhi, u, ulo, uhi)
End Function
Function zyv (y)
zyv = zLerplh(ylo, yhi, v, vlo, vhi)
End Function
Function zLerplh (ylo, yhi, x, xlo, xhi)
zLerplh = ylo + (x - xlo) / (xhi - xlo) * (yhi - ylo)
End Function
Function zBetween (x, a, b)
If x >= a And x <= b Then zBetween = 1
End Function
Function zMax (a, b)
If a > b Then zMax = a Else zMax = b
End Function
Function zMin (a, b)
If a < b Then zMin = a Else zMin = b
End Function
Sub zSystem
While InKey$ = "": _Limit 60: Wend
System
End Sub