lib/libm/src/w_log.c

   1 /* @(#)w_log.c 5.1 93/09/24 */
   2 /*
   3  * ====================================================
   4  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   5  *
   6  * Developed at SunPro, a Sun Microsystems, Inc. business.
   7  * Permission to use, copy, modify, and distribute this
   8  * software is freely granted, provided that this notice
   9  * is preserved.
  10  * ====================================================
  11  */
  12
  13 #include <sys/cdefs.h>
  14 #if defined(LIBM_SCCS) && !defined(lint)
  15 __RCSID("$NetBSD: w_log.c,v 1.10 2007/08/20 16:01:40 drochner Exp $");
  16 #endif
  17
  18 /*
  19  * wrapper log(x)
  20  */
  21
  22 #include "namespace.h"
  23 #include "math.h"
  24 #include "math_private.h"
  25
  26 #ifdef __weak_alias
  27 __weak_alias(log, _log)
  28 #endif
  29
  30 double
  31 log(double x)           /* wrapper log */
  32 {
  33 #ifdef _IEEE_LIBM
  34         return __ieee754_log(x);
  35 #else
  36         double z;
  37         z = __ieee754_log(x);
  38         if(_LIB_VERSION == _IEEE_ || isnan(x) || x > 0.0) return z;
  39         if(x==0.0)
  40             return __kernel_standard(x,x,16); /* log(0) */
  41         else
  42             return __kernel_standard(x,x,17); /* log(x<0) */
  43 #endif
  44 }