Routine Name: residual
Author: David Merkley
Language: Python
Description/Purpose: finds the residual of an approximation
Input: matrix, vector and vector
Output: the approximation
Implementation/Code:
def residual(A, b, x):
n = len(b)
r = [1.0 * ri for ri in b]
for i in range(n):
for j in range(n):
r[i] -= A[i][j] * x[j]
return r