my program is basically:

` ``input "f'(x,y)=', str1 for x from Xmin to Xmax, pi/6 intervals // if not pi/6, then what? too small, the screen is black. too big, the picture comes out all messed up for y from Ymin to Ymax expr(str1→D Line(x0,y0,x1,y1 // too lazy to type it out and i dont have my calc handy End End`

what can i do? ]]>