Diagonal Preconditioner Apply

Problem

Apply the diagonal (Jacobi) preconditioner to residual r, returning z with

z[i] = r[i] / A[i][i]

Assume all diagonal entries of A are nonzero.

Hint

This is one application of the inverse diagonal of A to a vector.

case 1

in: [[[2,0],[0,4]],[2,8]]

expected: [1,2]

case 2

in: [[[1,1],[1,3]],[4,8]]

expected: [4,2.6666666666666665]

case 3

in: [[[5]],[10]]

expected: [2]

case 4

in: [[[-2,0],[0,1]],[1,-1]]

expected: [-0.5,-1]

Starter codePython

def apply_diagonal_preconditioner(A, r):
    # Your code here
    pass

4 test cases · run your code against them in the editor