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set the correct noise floor for svds solver test #783

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Merged
Intron7 merged 1 commit into from
Sep 1, 2026
Merged

set the correct noise floor for svds solver test #783

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11 changes: 7 additions & 4 deletions tests/test_pca.py
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Original file line number Diff line number Diff line change
Expand Up @@ -923,10 +923,13 @@ def test_svd_sign_determinism(self, svd_func):
U1, s1, Vt1 = svd_func(X_gpu, k=k, rng=0)
U2, s2, Vt2 = svd_func(X_gpu, k=k, rng=0)

# Results should be identical (atol for GPU floating-point rounding variations)
np.testing.assert_allclose(U1.get(), U2.get(), rtol=1e-10, atol=1e-14)
np.testing.assert_allclose(s1.get(), s2.get(), rtol=1e-10, atol=1e-14)
np.testing.assert_allclose(Vt1.get(), Vt2.get(), rtol=1e-10, atol=1e-14)
# Results should be identical up to cuSPARSE noise: A.T @ u SpMV uses
# atomics with no bitwise-determinism guarantee, and Lanczos restarts
# amplify the ULP differences to ~1e-9 rel / ~5e-14 abs (measured on
# T4 and Blackwell), so tolerances sit 10-20x above that noise floor.
np.testing.assert_allclose(U1.get(), U2.get(), rtol=1e-8, atol=1e-12)
np.testing.assert_allclose(s1.get(), s2.get(), rtol=1e-8, atol=1e-12)
np.testing.assert_allclose(Vt1.get(), Vt2.get(), rtol=1e-8, atol=1e-12)

def test_mean_centered_operator(self):
"""Test that the mean-centered operator works correctly."""
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