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Fix clog10 (-0 +/- 0i) (bug 16362)
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: <libc-alpha at sourceware dot org>
- Date: Fri, 28 Mar 2014 15:19:49 +0000
- Subject: Fix clog10 (-0 +/- 0i) (bug 16362)
- Authentication-results: sourceware.org; auth=none
This patch fixes the imaginary part of clog10 (-0 +/- 0i), which
should be +/-pi / log(10) by analogy with clog (the functions were
wrongly returning a result with imaginary part +/-pi, same as for
clog, and the tests matched the incorrect result, though both
functions and tests were correct for the similar case of clog10 (-inf
+/- 0i)). Tested x86_64 and x86.
2014-03-28 Joseph Myers <joseph@codesourcery.com>
[BZ #16362]
* math/s_clog10.c (M_PI_LOG10E): New macro.
(__clog10): Use M_PI_LOG10E instead of M_PI when real and
imaginary parts are 0.
* math/s_clog10f.c (M_PI_LOG10Ef): New macro.
(__clog10f): Use M_PI_LOG10Ef instead of M_PI when real and
imaginary parts are 0.
* math/s_clog10l.c (M_PI_LOG10El): New macro.
(__clog10l): Use M_PI_LOG10El instead of M_PIl when real and
imaginary parts are 0.
* math/libm-test.inc (clog10_test_data): Update expected results
for when real and imaginary parts are 0.
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 9c4c2bf..cefcb96 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -6130,8 +6130,8 @@ clog_test (void)
static const struct test_c_c_data clog10_test_data[] =
{
- TEST_c_c (clog10, minus_zero, 0, minus_infty, M_PIl, DIVIDE_BY_ZERO_EXCEPTION),
- TEST_c_c (clog10, minus_zero, minus_zero, minus_infty, -M_PIl, DIVIDE_BY_ZERO_EXCEPTION),
+ TEST_c_c (clog10, minus_zero, 0, minus_infty, M_PI_LOG10El, DIVIDE_BY_ZERO_EXCEPTION),
+ TEST_c_c (clog10, minus_zero, minus_zero, minus_infty, -M_PI_LOG10El, DIVIDE_BY_ZERO_EXCEPTION),
TEST_c_c (clog10, 0, 0, minus_infty, 0.0, DIVIDE_BY_ZERO_EXCEPTION),
TEST_c_c (clog10, 0, minus_zero, minus_infty, minus_zero, DIVIDE_BY_ZERO_EXCEPTION),
diff --git a/math/s_clog10.c b/math/s_clog10.c
index 417d561..e757879 100644
--- a/math/s_clog10.c
+++ b/math/s_clog10.c
@@ -25,6 +25,9 @@
/* log_10 (2). */
#define M_LOG10_2 0.3010299956639811952137388947244930267682
+/* pi * log10 (e). */
+#define M_PI_LOG10E 1.364376353841841347485783625431355770210
+
__complex__ double
__clog10 (__complex__ double x)
{
@@ -35,7 +38,7 @@ __clog10 (__complex__ double x)
if (__glibc_unlikely (rcls == FP_ZERO && icls == FP_ZERO))
{
/* Real and imaginary part are 0.0. */
- __imag__ result = signbit (__real__ x) ? M_PI : 0.0;
+ __imag__ result = signbit (__real__ x) ? M_PI_LOG10E : 0.0;
__imag__ result = __copysign (__imag__ result, __imag__ x);
/* Yes, the following line raises an exception. */
__real__ result = -1.0 / fabs (__real__ x);
diff --git a/math/s_clog10f.c b/math/s_clog10f.c
index a9120e0..ca2cdf4 100644
--- a/math/s_clog10f.c
+++ b/math/s_clog10f.c
@@ -25,6 +25,9 @@
/* log_10 (2). */
#define M_LOG10_2f 0.3010299956639811952137388947244930267682f
+/* pi * log10 (e). */
+#define M_PI_LOG10Ef 1.364376353841841347485783625431355770210f
+
__complex__ float
__clog10f (__complex__ float x)
{
@@ -35,7 +38,7 @@ __clog10f (__complex__ float x)
if (__glibc_unlikely (rcls == FP_ZERO && icls == FP_ZERO))
{
/* Real and imaginary part are 0.0. */
- __imag__ result = signbit (__real__ x) ? M_PI : 0.0;
+ __imag__ result = signbit (__real__ x) ? M_PI_LOG10Ef : 0.0;
__imag__ result = __copysignf (__imag__ result, __imag__ x);
/* Yes, the following line raises an exception. */
__real__ result = -1.0 / fabsf (__real__ x);
diff --git a/math/s_clog10l.c b/math/s_clog10l.c
index ac33a8f..cdb5d61 100644
--- a/math/s_clog10l.c
+++ b/math/s_clog10l.c
@@ -32,6 +32,9 @@
/* log_10 (2). */
#define M_LOG10_2l 0.3010299956639811952137388947244930267682L
+/* pi * log10 (e). */
+#define M_PI_LOG10El 1.364376353841841347485783625431355770210L
+
__complex__ long double
__clog10l (__complex__ long double x)
{
@@ -42,7 +45,7 @@ __clog10l (__complex__ long double x)
if (__glibc_unlikely (rcls == FP_ZERO && icls == FP_ZERO))
{
/* Real and imaginary part are 0.0. */
- __imag__ result = signbit (__real__ x) ? M_PIl : 0.0;
+ __imag__ result = signbit (__real__ x) ? M_PI_LOG10El : 0.0;
__imag__ result = __copysignl (__imag__ result, __imag__ x);
/* Yes, the following line raises an exception. */
__real__ result = -1.0 / fabsl (__real__ x);
--
Joseph S. Myers
joseph@codesourcery.com