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66 lines
1.7 KiB
Python
66 lines
1.7 KiB
Python
5 years ago
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from __future__ import division, print_function, absolute_import
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import numpy as np
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from numpy.testing import assert_equal, assert_allclose, assert_
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from scipy.sparse.linalg.isolve import minres
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import pytest
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from pytest import raises as assert_raises
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from .test_iterative import assert_normclose
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def get_sample_problem():
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# A random 10 x 10 symmetric matrix
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np.random.seed(1234)
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matrix = np.random.rand(10, 10)
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matrix = matrix + matrix.T
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# A random vector of length 10
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vector = np.random.rand(10)
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return matrix, vector
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def test_singular():
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A, b = get_sample_problem()
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A[0, ] = 0
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b[0] = 0
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xp, info = minres(A, b)
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assert_equal(info, 0)
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assert_normclose(A.dot(xp), b, tol=1e-5)
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@pytest.mark.skip(reason="Skip Until gh #6843 is fixed")
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def test_gh_6843():
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"""check if x0 is being used by tracing iterates"""
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A, b = get_sample_problem()
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# Random x0 to feed minres
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np.random.seed(12345)
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x0 = np.random.rand(10)
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trace = []
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def trace_iterates(xk):
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trace.append(xk)
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minres(A, b, x0=x0, callback=trace_iterates)
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trace_with_x0 = trace
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trace = []
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minres(A, b, callback=trace_iterates)
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assert_(not np.array_equal(trace_with_x0[0], trace[0]))
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def test_shift():
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A, b = get_sample_problem()
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shift = 0.5
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shifted_A = A - shift * np.eye(10)
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x1, info1 = minres(A, b, shift=shift)
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x2, info2 = minres(shifted_A, b)
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assert_equal(info1, 0)
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assert_allclose(x1, x2, rtol=1e-5)
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def test_asymmetric_fail():
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"""Asymmetric matrix should raise `ValueError` when check=True"""
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A, b = get_sample_problem()
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A[1, 2] = 1
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A[2, 1] = 2
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with assert_raises(ValueError):
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xp, info = minres(A, b, check=True)
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