Coverage for src/pymor/la/inverse: 58%

# This file is part of the pyMOR project (http://www.pymor.org).

# Copyright Holders: Rene Milk, Stephan Rave, Felix Schindler

# License: BSD 2-Clause License (http://opensource.org/licenses/BSD-2-Clause)

from __future__ import absolute_import, division, print_function

import numpy as np

def inv_two_by_two(A):

'''Efficiently compute the inverses of an array of 2x2-matrices ::

| retval[i1,...,ik,m,n] = numpy.linalg.inv(A[i1,...,ik,:,:]).

'''

assert A.shape[-1] == A.shape[-2] == 2, 'Wrong shape of argument.'

D = A[..., 0, 0] * A[..., 1, 1] - A[..., 1, 0] * A[..., 0, 1]

D = 1 / D

INV = np.empty_like(A)

INV[..., 0, 0] = A[..., 1, 1]

INV[..., 1, 1] = A[..., 0, 0]

INV[..., 1, 0] = - A[..., 1, 0]

INV[..., 0, 1] = - A[..., 0, 1]

INV *= D[..., np.newaxis, np.newaxis]

return INV

def inv_transposed_two_by_two(A):

'''Efficiently compute the tranposed inverses of an array of 2x2-matrices ::