a=2 b = 30 zzdraw_line a b a=0.0077 b=1.077 c=55 zzdraw_parabola a b c a b local t x y zzgrid t=0 loop 10000 [x=-400+ 800*t y = a*x + b t=t+1/10000 jt x y color red [circle 1]] a b c local t x y zzgrid t=0 loop 10000 [x=-400+ 800*t y = a*x^2 + b*x + c t=t+1/10000 jt x y color blue [circle 1]] color lightgrey [ spin 4 [ mirror [ repeat 100 [ fd 1000 bk 2000 jt 10 0 ] jt 0 0 ] ] ] spin 4 [fd 1000 jt 0 0]