'***********************************************
     '
     'Polar1.bas by Nally + April 2000
     'Released as open source
     '
     'Polar1.bas plots the function defined
     'by R = 2.5 + 2*sin(12*phi) using polar
     'coordinates.
     '
     'To change the function plotted, locate
     'the branch label [Plot.click]. The
     'function is defined a few lines below
     'that branch label.
     '
     '***********************************************

pi = 3.141592
     PlotType$ = "Markers"
     MarkerValue$ = "set"
     LineValue$ = "reset"
     Scalefactor = 1
     BiggestXY = 0
     xmin = 0
     xmax = 0
     ymin = 0
     ymax = 0

Dim R(360)
     Dim x(360)
     Dim y(360)
     Dim xscaled(360)
     Dim yscaled(360)
     Dim xplot(360)
     Dim yplot(360)

     NoMainWin
     WindowWidth = 440
     WindowHeight = 265

 Graphicbox #main.PlotArea, 214, 21, 200, 200
     Button #main.Plot, "Plot !", [Plot.click], UL, 25, 126, 170, 30
     Groupbox #main.groupbox4, "Plot Appearance", 26, 16, 168, 105
     Radiobutton #main.radioMarkers, " Plot markers", [markers.Set],      [markers.Set], 38, 46, 112, 20
     Radiobutton #main.radioLines, " Plot Lines", [Lines.Set], [Lines.Set],      38, 71, 96, 20
     Button #main.About, "About...", [About.click], UL, 30, 186, 74,      25
     Button #main.Quit, "Quit", [Quit.click], UL, 118, 186, 72, 25
     Open "Plotting Polar Coordinates" For Window As #main
     Print #main.PlotArea, "fill white; flush"
     Print #main, "font arial 10"
     Print #main, "trapclose [Quit.click]"

 GoSub [Print.Initial.Control.Values]

[main.inputLoop] 'wait here for input event
     Wait
     GoTo [main.inputLoop]

     [Quit.click]

     Close #main: End

[Print.Initial.Control.Values]

 Print #main.radioMarkers, "Set"
     Print #main.PlotArea, "fill white"

 Return

     [markers.Set]

 Print #main.radioMarkers, "value? MarkerValue$"
     If (MarkerValue$ = "set") Then
     PlotType$ = "Markers"
     End If
     If (MarkerValue$ = "reset") Then
     PlotType$ = "Lines"
     End If

 GoTo [main.inputLoop]

     [Lines.Set]

 Print #main.radioLines, "value? LineValue$"
     If (LineValue$ = "set") Then
     PlotType$ = "Lines"
     End If
     If (LineValue$ = "reset") Then
     PlotType$ = "Markers"
     End If

 GoTo [main.inputLoop]

     [Plot.click]

 'for all angles between zero and 360 degrees,
     'find the value of R as defined by
     'R = 2.5 + 2*sin(12*phi)
     For degree = 0 to 360
     phi = (degree/360) *(2*pi)
     R(degree) = 2.5 + 2*Sin(12*phi)
     Next degree

 'Convert polar coordinates to
     'cartesian coordinates
     For degree = 0 to 360
     phi = (degree/360) * (2*pi)
     x(degree) = R(degree) * Cos(phi)
     y(degree) = R(degree) * Sin(phi)
     Next degree

 'Find the extreme values of all cartesian
     'x and y values as a prelude to
     'finding the scalefactor
     xmax = 0
     xmin = 0
     ymax = 0
     ymin = 0

 For degree = 0 to 360
     If (x(degree) > xmax) Then xmax = x(degree)
     If (x(degree) < xmin) Then xmin = x(degree)
     If (y(degree) > ymax) Then ymax = y(degree)
     If (y(degree) < ymin) Then ymin = y(degree)
     Next degree

 BiggestXY = 0
     If (abs(xmax) > BiggestXY) Then BiggestXY = abs(xmax)
     If (abs(xmin) > BiggestXY) Then BiggestXY = abs(xmin)
     If (abs(ymax) > BiggestXY) Then BiggestXY = abs(ymax)
     If (abs(ymin) > BiggestXY) Then BiggestXY = abs(ymin)

     'Establish the scalefactor
     Scalefactor = 90 / BiggestXY

 'Create a scaled set of the cartesian coordinates
     'so that the data will plot nicely in the Graphicbox
     For degree = 0 to 360
     xscaled(degree) = Scalefactor * x(degree)
     yscaled(degree) = Scalefactor * y(degree)
     Next degree

 'Shift the data set to the center of the
     'Graphicbox, while also reversing the
     'direction of y.
     For degree = 0 to 360
     xplot(degree) = 100 + xscaled(degree)
     yplot(degree) = 100 - yscaled(degree)
     Next degree

 If (PlotType$ = "Lines") Then [Skip.To.Lines]

 'If markers have been selected, plot markers
     Print #main.PlotArea, "discard"
     Print #main.PlotArea, "cls"
     Print #main.PlotArea, "fill white"
     Print #main.PlotArea, "down"

 For degree = 0 to 360
     Print #main.PlotArea, "place " + Str$(xplot(degree)) + " "      + Str$(yplot(degree))
     Print #main.PlotArea, "circle 2"
     Next degree

 GoTo [Plotting.Accomplished]

 [Skip.To.Lines]

 'If lines have been selected, plot lines
     Print #main.PlotArea, "discard"
     Print #main.PlotArea, "cls"
     Print #main.PlotArea, "fill white"
     Print #main.PlotArea, "down"

 For degree = 1 to 360
     xplot1 = xplot(degree - 1)
     yplot1 = yplot(degree - 1)
     xplot2 = xplot(degree)
     yplot2 = yplot(degree)

 Print #main.PlotArea, "line " + Str$(xplot1) + " " +      Str$(yplot1) + " " + _
     Str$(xplot2) + " " + Str$(yplot2)
     Next degree

 [Plotting.Accomplished]

 Print #main.PlotArea, "flush"

 GoTo [main.inputLoop]

[About.click]

 Notice "About Plotting Polar Coordinates" + Chr$(13) + _
     "By Nally + April 2000 " + Chr$(13) + _
     "Made with Liberty Basic " + Chr$(13) + _
     "Released as open source "
     GoTo [main.inputLoop]