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-rw-r--r--math/s_cacoshf.c14
1 files changed, 9 insertions, 5 deletions
diff --git a/math/s_cacoshf.c b/math/s_cacoshf.c
index d634a1b756..fc716ac519 100644
--- a/math/s_cacoshf.c
+++ b/math/s_cacoshf.c
@@ -1,5 +1,5 @@
/* Return arc hyperbole cosine for float value.
- Copyright (C) 1997, 2006, 2011 Free Software Foundation, Inc.
+ Copyright (C) 1997-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
@@ -66,10 +66,14 @@ __cacoshf (__complex__ float x)
}
/* The factor 16 is just a guess. */
else if (16.0 * fabsf (__imag__ x) < fabsf (__real__ x))
- /* Kahan's formula which avoid cancellation through subtraction in
- some cases. */
- res = 2.0 * __clogf (__csqrtf ((x + 1.0) / 2.0)
- + __csqrtf ((x - 1.0) / 2.0));
+ {
+ /* Kahan's formula which avoid cancellation through subtraction in
+ some cases. */
+ res = 2.0 * __clogf (__csqrtf ((x + 1.0) / 2.0)
+ + __csqrtf ((x - 1.0) / 2.0));
+ if (signbit (__real__ res))
+ __real__ res = 0.0f;
+ }
else
{
__complex__ float y;