cosine interpolation

1def cosineInterpolate(y1, y2, x)
2{
3   xv = (1 - cos(x * 3.1415927)) / 2
4   return y1 + (y2 - y1) * xv
5}
6

1def linearInterpolate(y1, y2, x):
2  return y1 + (y2 - y1) * x
3  

1def cosineInterpolate(y1, y2, x):
2   xv = (1 - cos(x * 3.1415927)) / 2
3   return y1 + (y2 - y1) * xv