'02 By Axel Nordin
'Input functions in y1 - y8
'Define size of window by setting XMax, XMin, YMax, YMin
'To get a smoother graph set Detail to a higher value
'To get a dotted graph set Lined to 0

sw = screen width
sh = screen height

cls

resize console 0, 0, sw, sh


XMin = -10
YMin = -10
XMax = 10
YMax = 10
Detail = 10
Lined = 1

def fn y1( x ) = x
def fn y2( x ) = x^2
def fn y3( x ) = -x^2
def fn y4( x ) = -x
def fn y5( x ) = 1/x^2
def fn y6( x ) = -1/x^2
def fn y7( x ) = 1/sqr(1+x^2)
def fn y8( x ) = -1/sqr(1+x^2)

gosub Init

for nf = 1 to 8
   gosub DrawGraph
next

end
Init:
   Detail = 1/Detail
   XScl = sw/(XMax - XMin)'Scale = pixels/graph unit
   YScl = sh/(YMax - YMin)

   OriX = (sw-(Xmax - 0 )*XScl)'find the origo by setting x,y = 0
   OriY = sh-(sh-(YMax - 0)*YScl)' The screen pos is found by finding the distance between the point and the XYMax and the converting it into screen coordinates
   Line OriX, 0, OriX, sh
   Line 0, OriY, sw, OriY
return

DrawGraph:
   XD = XMin : gosub GetfXD
   moveto (sw-(Xmax - XMin )*XScl), sh-(sh-(YMax - fY )*YScl)
   
   forecolor 35535, 65535, 0
   for x = XMin to XMax Step Detail
      Xs = (sw-(Xmax - x)*XScl)'Get the screen coordinates
      XD = x : gosub GetfXD
      Ys = sh-(sh-(YMax - fY )*YScl)
      if Lined = 1 then
         lineto Xs, Ys
         moveto Xs, Ys
      else
         plot Xs, Ys
      end if
   next
return

GetfXD:
   select case nf
      case 1:
         fY = fn y1( XD )
      case 2:
         fY = fn y2( XD )
      case 3:
         fY = fn y3( XD )
      case 4:
         fY = fn y4( XD )
      case 5:
         fY = fn y5( XD )
      case 6:
         fY = fn y6( XD )
      case 7:
         fY = fn y7( XD )
      case 8:
         fY = fn y8( XD )
   end select
return