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authorDavid S. Miller <davem@davemloft.net>2012-11-19 15:26:52 -0800
committerDavid S. Miller <davem@davemloft.net>2012-11-19 15:31:24 -0800
commit6d33cc9d9bde501e0906c42ee396d42cb4ca603c (patch)
treefa106d1ac0b43e69180ba0e497321d56210d4a92
parent877f2d8e8def5a278e4b9f4e4dc378f7f8a653b8 (diff)
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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.
-rw-r--r--ChangeLog10
-rw-r--r--math/libm-test.inc5
-rw-r--r--sysdeps/ieee754/ldbl-128/s_atanl.c17
-rw-r--r--sysdeps/sparc/fpu/libm-test-ulps3
-rw-r--r--sysdeps/x86_64/fpu/libm-test-ulps3
5 files changed, 38 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog
index f2e166b2e2..7e85f77016 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -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]
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 0b254e1738..2a60557fd9 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -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);
diff --git a/sysdeps/ieee754/ldbl-128/s_atanl.c b/sysdeps/ieee754/ldbl-128/s_atanl.c
index 0138e792aa..adac0a79e7 100644
--- a/sysdeps/ieee754/ldbl-128/s_atanl.c
+++ b/sysdeps/ieee754/ldbl-128/s_atanl.c
@@ -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;
diff --git a/sysdeps/sparc/fpu/libm-test-ulps b/sysdeps/sparc/fpu/libm-test-ulps
index ec0ad66204..432e01181a 100644
--- a/sysdeps/sparc/fpu/libm-test-ulps
+++ b/sysdeps/sparc/fpu/libm-test-ulps
@@ -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
diff --git a/sysdeps/x86_64/fpu/libm-test-ulps b/sysdeps/x86_64/fpu/libm-test-ulps
index 4767be94db..f33dfed3df 100644
--- a/sysdeps/x86_64/fpu/libm-test-ulps
+++ b/sysdeps/x86_64/fpu/libm-test-ulps
@@ -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