graphs slope fields with color. change the string in the bottom line to the derivative to be displayed.
from math import * from kandinsky import * global x global y def hcolor(h): h/=360 r=255*(1,2-6*h,0,6*h-4)[((0<=h and h<1/6) or (5/6<=h and h<=1),1/6<=h and h<1/3,1/3<=h and h<2/3, 2/3<=h and h<5/6).index(True)] g=255*(6*h,1,4-6*h,0)[(0<=h and h<1/6,1/6<=h and h<1/2,1/2<=h and h<2/3,2/3<=h and h<=1).index(True)] b=255*(0,6*h-2,1,6-6*h)[(0<=h and h<1/3,1/3<=h and h<1/2,1/2<=h and h<5/6,5/6<=h and h<=1).index(True)] return color(int(r),int(g),int(b)) def run(d): global x global y y=56 for gy in range(0,111): x=-80 for gx in range(0,160): try: h=(atan2(eval(d),1) + pi/2)/pi*360 except ZeroDivisionError: h=0 c=hcolor(h) for k in range(gy*2,gy*2+2): for h in range(gx*2,gx*2+2): set_pixel(h,k,c) x+=1 y-=1 run("x/y")