cosine interpolation

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

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

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