From: Joseph Myers <joseph@codesourcery.com>
Date: Thu, 22 Nov 2012 14:57:22 +0000 (+0000)
Subject: Fix ldbl-128ibm hypotl inaccuracy for arguments with large ratio (bug 14868).
X-Git-Tag: glibc-2.17~121
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8e27e3cc453849158e069dbed0eea7b8113ab8ff;p=thirdparty%2Fglibc.git

Fix ldbl-128ibm hypotl inaccuracy for arguments with large ratio (bug 14868).
---

diff --git a/ChangeLog b/ChangeLog
index c2421fa10d4..69dd8fe2d82 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2012-11-22  Joseph Myers  <joseph@codesourcery.com>
 
+	[BZ #14868]
+	* sysdeps/ieee754/ldbl-128ibm/e_hypotl.c (__ieee754_hypotl):
+	Return a+b for ratio over 2**120, not 2**60.
+	* math/libm-test.inc (hypot_test): Add another test.
+
 	* math/libm-test.inc (clog_test): Use
 	UNDERFLOW_EXCEPTION_LDOUBLE_IBM on two tests.
 	(clog10_test): Likewise.
diff --git a/NEWS b/NEWS
index c17a5573f0d..94e1260137a 100644
--- a/NEWS
+++ b/NEWS
@@ -21,7 +21,7 @@ Version 2.17
   14638, 14645, 14648, 14652, 14660, 14661, 14669, 14672, 14683, 14694,
   14716, 14719, 14743, 14767, 14783, 14784, 14785, 14793, 14796, 14797,
   14801, 14805, 14807, 14809, 14811, 14815, 14821, 14822, 14824, 14828,
-  14831, 14835, 14838, 14856, 14863, 14865, 14866.
+  14831, 14835, 14838, 14856, 14863, 14865, 14866, 14868.
 
 * Port to ARM AArch64 contributed by Linaro.
 
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 74ef15b212e..21f46469de4 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -5730,6 +5730,8 @@ hypot_test (void)
 
   TEST_ff_f (hypot, 0.75L, 1.25L, 1.45773797371132511771853821938639577L);
 
+  TEST_ff_f (hypot, 1.0L, 0x1p-61L, 1.0L);
+
 #if !(defined TEST_FLOAT && defined TEST_INLINE)
   TEST_ff_f (hypot, 0x3p125L, 0x4p125L, 0x5p125L);
   TEST_ff_f (hypot, 0x1.234566p-126L, 0x1.234566p-126L, 1.891441686191081936598531534017449451173e-38L);
diff --git a/sysdeps/ieee754/ldbl-128ibm/e_hypotl.c b/sysdeps/ieee754/ldbl-128ibm/e_hypotl.c
index 00bfb15926d..ce21194cd59 100644
--- a/sysdeps/ieee754/ldbl-128ibm/e_hypotl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/e_hypotl.c
@@ -61,7 +61,7 @@ __ieee754_hypotl(long double x, long double y)
 	if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
 	a = fabsl(a);	/* a <- |a| */
 	b = fabsl(b);	/* b <- |b| */
-	if((ha-hb)>0x3c0000000000000LL) {return a+b;} /* x/y > 2**60 */
+	if((ha-hb)>0x780000000000000LL) {return a+b;} /* x/y > 2**120 */
 	k=0;
 	kld = 1.0L;
 	if(ha > 0x5f30000000000000LL) {	/* a>2**500 */