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glibc  2.9
s_nearbyint.c
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00001 /* Copyright (C) 2007 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003    Contributed by Richard Henderson.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <math.h>
00021 #include <math_ldbl_opt.h>
00022 
00023 #ifdef _IEEE_FP_INEXACT
00024 #error "Don't compile with -mieee-with-inexact"
00025 #endif
00026 
00027 double
00028 __nearbyint (double x)
00029 {
00030   double two52 = copysign (0x1.0p52, x);
00031   double r;
00032   
00033   r = x + two52;
00034   r = r - two52;
00035 
00036   /* nearbyint(-0.1) == -0, and in general we'll always have the same sign
00037      as our input.  */
00038   return copysign (r, x);
00039 }
00040 
00041 weak_alias (__nearbyint, nearbyint)
00042 #ifdef NO_LONG_DOUBLE
00043 strong_alias (__nearbyint, __nearbyintl)
00044 weak_alias (__nearbyint, nearbyintl)
00045 #endif
00046 #if LONG_DOUBLE_COMPAT(libm, GLIBC_2_1)
00047 compat_symbol (libm, __nearbyint, nearbyintl, GLIBC_2_1);
00048 #endif