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Fix spurious underflows in ldbl-128 atan implementation. 

With help from Joseph Myers.
	* sysdeps/ieee754/ldbl-128/s_atanl.c (__atanl): Handle tiny and
	very large arguments properly.
	* math/libm-test.inc (atan_test): New tests.
	(atan2_test): New tests.
	* sysdeps/sparc/fpu/libm-test-ulps: Update.
	* sysdeps/x86_64/fpu/libm-test-ulps: Update.
This commit is contained in:
David S. Miller 2012-11-19 15:26:52 -08:00
parent 877f2d8e8d
commit 6d33cc9d9b
5 changed files with 38 additions and 0 deletions
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10
ChangeLog
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@ -1,3 +1,13 @@
2012-11-19 David S. Miller <davem@davemloft.net>
With help from Joseph Myers.
* sysdeps/ieee754/ldbl-128/s_atanl.c (__atanl): Handle tiny and
very large arguments properly.
* math/libm-test.inc (atan_test): New tests.
(atan2_test): New tests.
* sysdeps/sparc/fpu/libm-test-ulps: Update.
* sysdeps/x86_64/fpu/libm-test-ulps: Update.
2012-11-19 Joseph Myers <joseph@codesourcery.com>
[BZ #14856]

5
math/libm-test.inc
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@ -1187,6 +1187,8 @@ atan_test (void)
TEST_f_f (atan, plus_infty, M_PI_2l);
TEST_f_f (atan, minus_infty, -M_PI_2l);
TEST_f_f (atan, nan_value, nan_value);
TEST_f_f (atan, max_value, M_PI_2l);
TEST_f_f (atan, -max_value, -M_PI_2l);
TEST_f_f (atan, 1, M_PI_4l);
TEST_f_f (atan, -1, -M_PI_4l);
@ -1295,6 +1297,9 @@ atan2_test (void)
TEST_ff_f (atan2, max_value, max_value, M_PI_4l);
TEST_ff_f (atan2, max_value, min_value, M_PI_2l);
TEST_ff_f (atan2, -max_value, -min_value, -M_PI_2l);
TEST_ff_f (atan2, 0.75L, 1, 0.643501108793284386802809228717322638L);
TEST_ff_f (atan2, -0.75L, 1.0L, -0.643501108793284386802809228717322638L);
TEST_ff_f (atan2, 0.75L, -1.0L, 2.49809154479650885165983415456218025L);

17
sysdeps/ieee754/ldbl-128/s_atanl.c
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@ -167,6 +167,7 @@ static const long double
q4 = 2.173623741810414221251136181221172551416E1L;
/* q5 = 1.000000000000000000000000000000000000000E0 */
static const long double huge = 1.0e4930L;
long double
__atanl (long double x)
@ -197,6 +198,22 @@ __atanl (long double x)
return atantbl[83];
}
if (k <= 0x3fc50000) /* |x| < 2**-58 */
{
/* Raise inexact. */
if (huge + x > 0.0)
return x;
}
if (k >= 0x40720000) /* |x| > 2**115 */
{
/* Saturate result to {-,+}pi/2 */
if (sign)
return -atantbl[83];
else
return atantbl[83];
}
if (sign)
x = -x;

3
sysdeps/sparc/fpu/libm-test-ulps
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@ -102,6 +102,9 @@ float: 1
ifloat: 1
ildouble: 1
ldouble: 1
Test "atan2 (-max_value, -min_value) == -pi/2":
float: 1
ifloat: 1
Test "atan2 (0.75, -1.0) == 2.49809154479650885165983415456218025":
float: 1
ifloat: 1

3
sysdeps/x86_64/fpu/libm-test-ulps
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@ -162,6 +162,9 @@ ldouble: 1
Test "atan2 (-0.75, -1.0) == -2.49809154479650885165983415456218025":
float: 1
ifloat: 1
Test "atan2 (-max_value, -min_value) == -pi/2":
float: 1
ifloat: 1
Test "atan2 (0.75, -1.0) == 2.49809154479650885165983415456218025":
float: 1
ifloat: 1