Fix cacos (+Inf + finite*i) in round-downward mode (bug 16928)
diff mbox

Message ID Pine.LNX.4.64.1405092326120.32339@digraph.polyomino.org.uk
State New
Headers show

Commit Message

Joseph Myers May 9, 2014, 11:26 p.m. UTC
According to C99/C11 Annex G, cacos applied to a value with real part
+Inf and finite imaginary part should produce a result with real part
+0.  glibc wrongly produces a result with real part -0 in FE_DOWNWARD
mode.  This patch fixes this by checking for zero results in the
relevant case of non-finite arguments (where there should never be a
result with -0 real part), and converts the tests of cacos to
ALL_RM_TEST.

Tested x86_64 and x86 and ulps updated accordingly.

2014-05-09  Joseph Myers  <joseph@codesourcery.com>

	[BZ #16928]
	* math/s_cacos.c (__cacos): Ensure zero real part of result from
	non-finite arguments is +0.
	* math/s_cacosf.c (__cacosf): Likewise.
	* math/s_cacosl.c (__cacosl): Likewise.
	* math/libm-test.inc (cacos_test): Use ALL_RM_TEST.
	* sysdeps/i386/fpu/libm-test-ulps: Update.
	* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.

Comments

Andreas Jaeger May 14, 2014, 10:25 a.m. UTC | #1
On 05/09/2014 07:26 PM, Joseph S. Myers wrote:
> According to C99/C11 Annex G, cacos applied to a value with real part
> +Inf and finite imaginary part should produce a result with real part
> +0.  glibc wrongly produces a result with real part -0 in FE_DOWNWARD
> mode.  This patch fixes this by checking for zero results in the
> relevant case of non-finite arguments (where there should never be a
> result with -0 real part), and converts the tests of cacos to
> ALL_RM_TEST.

ok, thanks,
Andreas

Patch
diff mbox

diff --git a/math/libm-test.inc b/math/libm-test.inc
index a4bf0b8..1cd8359 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -2617,9 +2617,7 @@  static const struct test_c_c_data cacos_test_data[] =
 static void
 cacos_test (void)
 {
-  START (cacos, 0);
-  RUN_TEST_LOOP_c_c (cacos, cacos_test_data, );
-  END_COMPLEX;
+  ALL_RM_TEST (cacos, 0, cacos_test_data, RUN_TEST_LOOP_c_c, END_COMPLEX);
 }
 
 static const struct test_c_c_data cacosh_test_data[] =
diff --git a/math/s_cacos.c b/math/s_cacos.c
index d0aaba4..2c22817 100644
--- a/math/s_cacos.c
+++ b/math/s_cacos.c
@@ -34,6 +34,8 @@  __cacos (__complex__ double x)
       y = __casin (x);
 
       __real__ res = (double) M_PI_2 - __real__ y;
+      if (__real__ res == 0.0)
+	__real__ res = 0.0;
       __imag__ res = -__imag__ y;
     }
   else
diff --git a/math/s_cacosf.c b/math/s_cacosf.c
index 9eaeeec..1c9d8b9 100644
--- a/math/s_cacosf.c
+++ b/math/s_cacosf.c
@@ -34,6 +34,8 @@  __cacosf (__complex__ float x)
       y = __casinf (x);
 
       __real__ res = (float) M_PI_2 - __real__ y;
+      if (__real__ res == 0.0f)
+	__real__ res = 0.0f;
       __imag__ res = -__imag__ y;
     }
   else
diff --git a/math/s_cacosl.c b/math/s_cacosl.c
index b9d3493..8688d3c 100644
--- a/math/s_cacosl.c
+++ b/math/s_cacosl.c
@@ -34,6 +34,8 @@  __cacosl (__complex__ long double x)
       y = __casinl (x);
 
       __real__ res = M_PI_2l - __real__ y;
+      if (__real__ res == 0.0L)
+	__real__ res = 0.0L;
       __imag__ res = -__imag__ y;
     }
   else
diff --git a/sysdeps/i386/fpu/libm-test-ulps b/sysdeps/i386/fpu/libm-test-ulps
index aea6c51..199e4ff 100644
--- a/sysdeps/i386/fpu/libm-test-ulps
+++ b/sysdeps/i386/fpu/libm-test-ulps
@@ -161,6 +161,54 @@  ifloat: 1
 ildouble: 2
 ldouble: 2
 
+Function: Real part of "cacos_downward":
+double: 2
+float: 1
+idouble: 2
+ifloat: 1
+ildouble: 2
+ldouble: 2
+
+Function: Imaginary part of "cacos_downward":
+double: 3
+float: 3
+idouble: 3
+ifloat: 3
+ildouble: 5
+ldouble: 5
+
+Function: Real part of "cacos_towardzero":
+double: 2
+float: 1
+idouble: 2
+ifloat: 1
+ildouble: 2
+ldouble: 2
+
+Function: Imaginary part of "cacos_towardzero":
+double: 3
+float: 3
+idouble: 3
+ifloat: 3
+ildouble: 5
+ldouble: 5
+
+Function: Real part of "cacos_upward":
+double: 2
+float: 2
+idouble: 2
+ifloat: 2
+ildouble: 2
+ldouble: 2
+
+Function: Imaginary part of "cacos_upward":
+double: 4
+float: 4
+idouble: 4
+ifloat: 4
+ildouble: 5
+ldouble: 5
+
 Function: Real part of "cacosh":
 double: 1
 float: 1
diff --git a/sysdeps/x86_64/fpu/libm-test-ulps b/sysdeps/x86_64/fpu/libm-test-ulps
index 4ba83a4..2369a78 100644
--- a/sysdeps/x86_64/fpu/libm-test-ulps
+++ b/sysdeps/x86_64/fpu/libm-test-ulps
@@ -184,6 +184,54 @@  ifloat: 2
 ildouble: 2
 ldouble: 2
 
+Function: Real part of "cacos_downward":
+double: 1
+float: 2
+idouble: 1
+ifloat: 2
+ildouble: 2
+ldouble: 2
+
+Function: Imaginary part of "cacos_downward":
+double: 5
+float: 3
+idouble: 5
+ifloat: 3
+ildouble: 5
+ldouble: 5
+
+Function: Real part of "cacos_towardzero":
+double: 1
+float: 2
+idouble: 1
+ifloat: 2
+ildouble: 2
+ldouble: 2
+
+Function: Imaginary part of "cacos_towardzero":
+double: 5
+float: 3
+idouble: 5
+ifloat: 3
+ildouble: 5
+ldouble: 5
+
+Function: Real part of "cacos_upward":
+double: 2
+float: 2
+idouble: 2
+ifloat: 2
+ildouble: 2
+ldouble: 2
+
+Function: Imaginary part of "cacos_upward":
+double: 4
+float: 4
+idouble: 4
+ifloat: 4
+ildouble: 5
+ldouble: 5
+
 Function: Real part of "cacosh":
 double: 1
 float: 2