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mattip opened this issue May 9, 2019 · 7 comments
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ENH: confirm accuracy of basic math functions #13515

mattip opened this issue May 9, 2019 · 7 comments
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01 - Enhancement 05 - Testing 23 - Wish List component: numpy._core

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@mattip
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mattip commented May 9, 2019

We do not verify results of our math functions (sin, cos, exp, log, ...) against a "gold standard" which makes changing the algorithms used to calculate them tricky. Python has a tests based on generating "true" values for certain interesting cases. We should explore adding these kinds of tests for the various built-in float and integer types, perhaps mpmath could help generate the "true" values.
@mattip
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mattip commented May 9, 2019

See also this email thread from 2012 with the author of the python test files on using mpfr to calculate the results

@seberg
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seberg commented May 9, 2019

Not sure it is relevant, but there was also just this to do testing for scipy on scipy-dev: https://mail.python.org/pipermail/scipy-dev/2019-May/023508.html

@juliantaylor
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juliantaylor commented May 9, 2019 •
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glibc has a testsuite for math functions which could be used as input for what is interesting to test:
https://sourceware.org/git/?p=glibc.git;a=blob;f=math/README.libm-test;h=53172bbff87ff54e2f93ecc142fb607a2b350650;hb=HEAD

see all the test-out files, they include input output and exceptions
other files define the current maximal error for all the different architectures and rounding modes

@r-devulap r-devulap mentioned this issue May 18, 2019
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mattip commented May 22, 2019

Python has a test suite for complex numbers when testing cmath based on a text file of results, we should be consistent with these results or document why we differ.

@mattip mattip mentioned this issue Jul 5, 2019
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This was referenced Jul 14, 2019
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@r-devulap
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PR #14048 addressed this issue for float32 exp, log, sin and cos.

@r-devulap r-devulap mentioned this issue Jul 16, 2021
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PR #19485 can hopefully close this issue?

@mattip
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mattip commented Mar 16, 2023

Closing, we now have better accuracy tests

@mattip mattip closed this as completed Mar 16, 2023
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