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PATCH: BZ 552: Wrong return values for tgamma (0) and tgamma (-0)
- From: "H. J. Lu" <hjl at lucon dot org>
- To: GNU C Library <libc-alpha at sources dot redhat dot com>
- Date: Tue, 16 Nov 2004 17:54:50 -0800
- Subject: PATCH: BZ 552: Wrong return values for tgamma (0) and tgamma (-0)
This patch makes tgamma (0) and tgamma (-0) to conform F.9.5.4 in C99.
It seems that tgamma and gamma aren't the same. gamma (0) raises
the invalid exception while tgamma (0) raises the divide-by-zero
exception. The internal __ieee754_gamma_r, which is used to implement
both tgamma and gamma, always raises the invalid exception on 0. I
have to clear FE_INVALID for tgamma.
H.J.
----
2004-11-16 H.J. Lu <hongjiu.lu@intel.com>
[BZ #552]
* math/libm-test.inc (tgamma_test): Update tgamma (0) and
tgamma (-0).
* sysdeps/generic/w_tgamma.c (__tgamma): Properly handle
|x| == 0.
* sysdeps/generic/w_tgammaf.c (__tgammaf): Likewise.
* sysdeps/generic/w_tgammal.c (__tgammal): Likewise.
* sysdeps/ieee754/k_standard.c (__kernel_standard): Handle
tgamma (0) and tgamma (-0).
--- libc/math/libm-test.inc.tgamma 2004-09-27 11:54:13.000000000 -0700
+++ libc/math/libm-test.inc 2004-11-16 16:16:56.497767214 -0800
@@ -4132,8 +4132,8 @@ tgamma_test (void)
START (tgamma);
TEST_f_f (tgamma, plus_infty, plus_infty);
- TEST_f_f (tgamma, 0, nan_value, INVALID_EXCEPTION);
- TEST_f_f (tgamma, minus_zero, nan_value, INVALID_EXCEPTION);
+ TEST_f_f (tgamma, 0, plus_infty, DIVIDE_BY_ZERO_EXCEPTION);
+ TEST_f_f (tgamma, minus_zero, minus_infty, DIVIDE_BY_ZERO_EXCEPTION);
/* tgamma (x) == NaN plus invalid exception for integer x <= 0. */
TEST_f_f (tgamma, -2, nan_value, INVALID_EXCEPTION);
TEST_f_f (tgamma, minus_infty, nan_value, INVALID_EXCEPTION);
--- libc/sysdeps/generic/w_tgamma.c.tgamma 2001-02-16 17:45:34.000000000 -0800
+++ libc/sysdeps/generic/w_tgamma.c 2004-11-16 16:59:47.447835314 -0800
@@ -39,8 +39,10 @@ static char rcsid[] = "$NetBSD: w_gamma.
if(_LIB_VERSION == _IEEE_) return y;
if(!__finite(y)&&__finite(x)) {
- if(__floor(x)==x&&x<=0.0)
- return __kernel_standard(x,x,41); /* tgamma pole */
+ if (x == 0.0)
+ return __kernel_standard(x,x,50); /* tgamma pole */
+ else if(__floor(x)==x&&x<0.0)
+ return __kernel_standard(x,x,41); /* tgamma domain */
else
return __kernel_standard(x,x,40); /* tgamma overflow */
}
--- libc/sysdeps/generic/w_tgammaf.c.tgamma 2001-02-16 17:45:39.000000000 -0800
+++ libc/sysdeps/generic/w_tgammaf.c 2004-11-16 17:13:40.091060684 -0800
@@ -37,8 +37,11 @@ static char rcsid[] = "$NetBSD: w_gammaf
if(_LIB_VERSION == _IEEE_) return y;
if(!__finitef(y)&&__finitef(x)) {
- if(__floorf(x)==x&&x<=(float)0.0)
+ if (x == (float)0.0)
/* tgammaf pole */
+ return (float)__kernel_standard((double)x,(double)x,150);
+ else if(__floorf(x)==x&&x<(float)0.0)
+ /* tgammaf domain */
return (float)__kernel_standard((double)x,(double)x,141);
else
/* tgammaf overflow */
--- libc/sysdeps/generic/w_tgammal.c.tgamma 2001-02-16 17:45:44.000000000 -0800
+++ libc/sysdeps/generic/w_tgammal.c 2004-11-16 17:13:30.545290296 -0800
@@ -42,8 +42,10 @@ static char rcsid[] = "$NetBSD: $";
if(_LIB_VERSION == _IEEE_) return y;
if(!__finitel(y)&&__finitel(x)) {
- if(__floorl(x)==x&&x<=0.0)
- return __kernel_standard(x,x,241); /* tgamma pole */
+ if(x==0.0)
+ return __kernel_standard(x,x,250); /* tgamma pole */
+ else if(__floorl(x)==x&&x<0.0)
+ return __kernel_standard(x,x,241); /* tgamma domain */
else
return __kernel_standard(x,x,240); /* tgamma overflow */
}
--- libc/sysdeps/ieee754/k_standard.c.tgamma 2001-06-06 05:46:35.000000000 -0700
+++ libc/sysdeps/ieee754/k_standard.c 2004-11-16 17:11:41.330358516 -0800
@@ -17,6 +17,7 @@ static char rcsid[] = "$NetBSD: k_standa
#include "math.h"
#include "math_private.h"
#include <errno.h>
+#include <fenv.h>
#include <assert.h>
@@ -832,7 +833,7 @@ static double zero = 0.0; /* used as con
case 40:
case 140:
case 240:
- /* gamma(finite) overflow */
+ /* tgamma(finite) overflow */
exc.type = OVERFLOW;
exc.name = type < 100 ? "tgamma" : (type < 200
? "tgammaf" : "tgammal");
@@ -846,7 +847,7 @@ static double zero = 0.0; /* used as con
case 41:
case 141:
case 241:
- /* gamma(-integer) or gamma(0) */
+ /* tgamma(-integer) */
exc.type = SING;
exc.name = type < 100 ? "tgamma" : (type < 200
? "tgammaf" : "tgammal");
@@ -973,8 +974,29 @@ static double zero = 0.0; /* used as con
__set_errno (EDOM);
}
break;
+ case 50:
+ case 150:
+ case 250:
+ /* tgamma(|x|==0) */
+#ifdef FE_INVALID
+ feclearexcept (FE_INVALID);
+#endif
+ exc.type = SING;
+ exc.name = type < 100 ? "tgamma" : (type < 200
+ ? "tgammaf" : "tgammal");
+ exc.retval = 1.0/x;
+ if (_LIB_VERSION == _POSIX_)
+ __set_errno (ERANGE);
+ else if (!matherr(&exc)) {
+ if (_LIB_VERSION == _SVID_) {
+ (void) WRITE2("tgamma: SING error\n", 18);
+ exc.retval = 1.0/x;
+ }
+ __set_errno (ERANGE);
+ }
+ break;
- /* #### Last used is 49/149/249 ### */
+ /* #### Last used is 50/150/250 ### */
}
return exc.retval;
}