T=d f ld
V=x
R=-1,1,0.25
F=(acos(x) > 0) + \
  2*(0 < acos(x)) + \
  4*(acos(x) < 0) + \
  8*(0 > acos(x))
C=fp_greater(fp_acos(x), 0) + \
  2*fp_less(0, fp_acos(x)) + \
  4*fp_less(fp_acos(x), 0) + \
  8*fp_greater(0, fp_acos(x))