Peter,
I would suggest
............
sn = sin(0.8 * f) * 160-x+160
cs = cos(1.2 * f) * 100-y+100
c2 = sqr(sn*sn + cs*cs)
............
to make it run ultimately fast. Oxygen doesn't have an optimizer to rearrange the code in such a way automatically. By the way, the language from which you took this snippet literally doesn't have any such optimization either.