From: Corinna Vinschen <vinschen@redhat.com>
To: newlib@sourceware.org
Subject: Re: [PATCH] libm: Fix 'gamma' and 'gammaf' functions. Clean up other gamma code. [v2]
Date: Fri, 4 Sep 2020 21:30:40 +0200 [thread overview]
Message-ID: <20200904193040.GX4127@calimero.vinschen.de> (raw)
In-Reply-To: <20200904162527.2145547-1-keithp@keithp.com>
On Sep 4 09:25, Keith Packard via Newlib wrote:
> The current gamma, gamma_r, gammaf and gammaf_r functions return
> |gamma(x)| instead of ln(|gamma(x)|) due to a change made back in 2002
> to the __ieee754_gamma_r implementation. This patch fixes that, making
> all of these functions map too their lgamma equivalents.
>
> To fix the underlying bug, the __ieee754_gamma functions have been
> changed to return gamma(x), removing the _r variants as those are no
> longer necessary. Their names have been changed to __ieee754_tgamma to
> avoid potential confusion from users.
>
> Now that the __ieee754_tgamma functions return the correctly signed
> value, the tgamma functions have been modified to use them.
>
> libm.a now exposes the following gamma functions:
>
> ln(|gamma(x)|):
>
> __ieee754_lgamma_r
> __ieee754_lgammaf_r
>
> lgamma
> lgamma_r
> gamma
> gamma_r
>
> lgammaf
> lgammaf_r
> gammaf
> gammaf_r
>
> lgammal (on machines where long double is double)
>
> gamma(x):
>
> __ieee754_tgamma
> __ieee754_tgammaf
> tgamma
> tgammaf
> tgammal (on machines where long double is double)
>
> Additional aliases for any of the above functions can be added if
> necessary; in particular, I'm not sure if we need to include
> __ieee754_gamma*_r functions (which would return ln(|(gamma(x)|).
>
> Signed-off-by: Keith Packard <keithp@keithp.com>
Pushed.
Thanks,
Corinna
next prev parent reply other threads:[~2020-09-04 19:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-04 16:25 Keith Packard
2020-09-04 19:30 ` Corinna Vinschen [this message]
2020-09-07 14:27 ` Jon Turney
2020-09-07 17:31 ` Keith Packard
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