libm: Fix 'gamma' and 'gammaf' functions. Clean up other gamma code. [v2]

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>

----

v2:
	Switch commit message to ASCII

1 files changed, 0 insertions, 32 deletions

diff --git a/newlib/libm/math/er_gamma.c b/newlib/libm/math/er_gamma.c
deleted file mode 100644
index 3c0e241..0000000
--- a/newlib/libm/math/er_gamma.c
+++ /dev/null
@@ -1,32 +0,0 @@
-
-/* @(#)er_gamma.c 5.1 93/09/24 */
-/*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunPro, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice 
- * is preserved.
- * ====================================================
- *
- */
-
-/* __ieee754_gamma_r(x, signgamp)
- * Reentrant version of the logarithm of the Gamma function 
- * with user provide pointer for the sign of Gamma(x). 
- *
- * Method: See __ieee754_lgamma_r
- */
-
-#include "fdlibm.h"
-
-#ifdef __STDC__
-	double __ieee754_gamma_r(double x, int *signgamp)
-#else
-	double __ieee754_gamma_r(x,signgamp)
-	double x; int *signgamp;
-#endif
-{
-	return __ieee754_exp (__ieee754_lgamma_r(x,signgamp));
-}