- degree = len(xs) - 1
-
- N = SR(0)
-
- for k in range(0, degree+1):
- term = divided_difference(xs[:k+1], ys[:k+1])
- term *= lagrange_psi(x, xs[:k])
- N += term
-
- return N
+ return sum( divided_difference(xs[:k+1], ys[:k+1])*lagrange_psi(x, xs[:k])
+ for k in xrange(len(xs)) )