Test test_hilbert_schmidt_inner_product_is_positive_definite[m6] fails on aarch64 and ppc64le

[ggardet]

Description of the issue
Test test_hilbert_schmidt_inner_product_is_positive_definite[m6] fails on openSUSE Tumbleweed aarch64/ppc64le

[  765s] =================================== FAILURES ===================================
[  765s] _________ test_hilbert_schmidt_inner_product_is_positive_definite[m6] __________
[  765s] 
[  765s] m = array([[ 0.5+0.5j, -0.5-0.5j],
[  765s]        [ 0.5+0.5j,  0.5+0.5j]])
[  765s] 
[  765s]     @pytest.mark.parametrize('m', (I, X, Y, Z, H, SQRT_X, SQRT_Y, SQRT_Z))
[  765s]     def test_hilbert_schmidt_inner_product_is_positive_definite(m):
[  765s]         v = cirq.hilbert_schmidt_inner_product(m, m)
[  765s] >       assert np.isreal(v)
[  765s] E       assert False
[  765s] E        +  where False = <function isreal at 0xffff928f8310>((2.000000000000001+4.930380657631324e-32j))
[  765s] E        +    where <function isreal at 0xffff928f8310> = np.isreal
[  765s] 
[  765s] cirq/linalg/operator_spaces_test.py:166: AssertionError

How to reproduce the issue
Run test suite on aarch64 or ppc64le.

Cirq version
0.9.1

[viathor]

@ggardet Do you have more information about how the test fails?

Everyone else: Anyone's got access to the platform? I think you can run this to reproduce:

pytest -k test_hilbert_schmidt_inner_product_is_positive_definite cirq-core/cirq/linalg/operator_spaces_test.py

[ggardet]

@ggardet Do you have more information about how the test fails?

I forgot to add the log, sorry. I added it to the 1st comment now.

[balopat]

A rounding error...e-32... we should just use np.isclose(np.imag(v), atol=1e-16) or similar.

[ggardet]

I can test a patch if needed.

[github-actions]

This issue is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 30 days

[vtomole]

@ggardet Please do.

[ggardet]

@ggardet Please do.

@vtomole Which patch could I test? I see nothing to test yet.

[github-actions]

This issue is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 30 days

[dabacon]

Could someone who has access to this architecture please see if the fix provided works?

@ggardet ?

[risicle]

We happen to be putting together the NixOS package for this at the moment and we're finding this and a few other tests are failing on aarch64-linux due to tolerance issues. Full log: https://hydra.nixos.org/log/df0xzjzyvn3g8g9pmaais8y8k5wv3pd3-python3.8-cirq-core-0.13.1.drv

[ggardet]

Could someone who has access to this architecture please see if the fix provided works?

@ggardet ?

Yes, the fix in #4636 make the test to pass. Thanks!

[vtomole]

@ggardet Awesome

@risicle Does this fix work for that NixOS package? Note, you'll need to test on the dev version of Cirq: pip install cirq==0.14.0.dev20211112014647

[dabacon]

@risicle added fixes for the tests you list. Could you verify these are now fine. Thanks!

[risicle]

Absolutely. 100%. Perfect - thankyou. 👍