Enabled tgamma test for bruteforce suite #2251
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svenvh
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Feb 6, 2025
| @@ -2111,6 +2111,8 @@ int reference_not(double x) | |||
| return r; | |||
| } | |||
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| double reference_tgamma(double x) { return tgamma(x); } | |||
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I am not sure if we can rely on libc's tgamma for the reference computation? Known Maximum Errors in Math Functions seems to indicate that most tgamma libc implementations have a rather large ULP value.
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Indeed, thanks! Computing reference values for tgamma seems challenging. As far as I understand, each implementation is subject to non-zero error. Please correct me if I am wrong at any point, I see few directions to follow:
- pre-computed high-precision values taken from
MatLabor similar software. This approach will definitely impact the source code with a separate path fortgammaprocessing. - limiting tgamma arguments for integral values which will result in zero error outcome. As with the previous proposition, this approach will result as a separate path for
tgammaprocessing. - implementing a procedure to compute
tgammareference values with maximum known-error. According to this paper OpenLibm contains tgamma implementation with error<1ULP. Moreover, license looks friendly for other open source projects. Then we could take into account the known-error by enlarging the error from table 65.
I will appreciate discussion over this subject, thanks!
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Fixes #507 according to work plan from issue description.