polyfit and eig regression tests fail after Windows 10 update to 2004

Tests are failing: FAILED …..\lib\tests\test_regression.py::TestRegression::test_polyfit_build - numpy.linalg.LinAlgError: SVD did not… FAILED …..\linalg\tests\test_regression.py::TestRegression::test_eig_build - numpy.linalg.LinAlgError: Eigenvalues … FAILED …..\ma\tests\test_extras.py::TestPolynomial::test_polyfit - numpy.linalg.LinAlgError: SVD did not converge i…

with exceptions:

err = 'invalid value', flag = 8
    def _raise_linalgerror_lstsq(err, flag):
>       raise LinAlgError("SVD did not converge in Linear Least Squares")
E       numpy.linalg.LinAlgError: SVD did not converge in Linear Least Squares
err        = 'invalid value'
flag       = 8

and

err = 'invalid value', flag = 8
    def _raise_linalgerror_eigenvalues_nonconvergence(err, flag):
>       raise LinAlgError("Eigenvalues did not converge")
E       numpy.linalg.LinAlgError: Eigenvalues did not converge
err        = 'invalid value'
flag       = 8

Steps taken:

• Create a VM
• Install latest Windows 10 and update to the latest version 2004 (10.0.19041)
• Install Python 3.8.3
• pip install pytest
• pip install numpy
• pip install hypothesis
• run tests in the package

Same happens issue happens when running on tests in the repository.

Version 1.19.0 of numpy

Am I missing any dependencies? Or is it just Windows going bonkers?

[mattip]

We have merged an update to OpenBLAS v0.3.12 and a local build using that version + windows update 2004 passes the test suite.

[bashtage]

The final fix is nearing release and is now in beta and release channels. Hopefully out next month.

Windows 10 build 19042.782

• We fixed an issue that causes the 64-bit fmod() and remainder() functions to damage the Floating Point Unit (FPU) stack.