5261 libm should stop using synonyms.h
5298 fabs is 0-sized, confuses dis(1) and others
Reviewed by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
Approved by: Gordon Ross <gwr@nexenta.com>

          --- old/usr/src/lib/libm/common/C/acosh.c
          +++ new/usr/src/lib/libm/common/C/acosh.c

   1    1  /*
   2    2   * CDDL HEADER START
   3    3   *
   4    4   * The contents of this file are subject to the terms of the
   5    5   * Common Development and Distribution License (the "License").
   6    6   * You may not use this file except in compliance with the License.
   7    7   *
   8    8   * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9    9   * or http://www.opensolaris.org/os/licensing.
  10   10   * See the License for the specific language governing permissions
  11   11   * and limitations under the License.
  12   12   *
  13   13   * When distributing Covered Code, include this CDDL HEADER in each
  14   14   * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15   15   * If applicable, add the following below this CDDL HEADER, with the
  16   16   * fields enclosed by brackets "[]" replaced with your own identifying
  17   17   * information: Portions Copyright [yyyy] [name of copyright owner]
  18   18   *
  19   19   * CDDL HEADER END

  20   20   */
  21   21  
  22   22  /*
  23   23   * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  24   24   */
  25   25  /*
  26   26   * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  27   27   * Use is subject to license terms.
  28   28   */
  29   29  
  30      -#pragma weak acosh = __acosh
       30 +#pragma weak __acosh = acosh
  31   31  
  32   32  /* INDENT OFF */
  33   33  /*
  34   34   * acosh(x)
  35   35   * Method :
  36   36   *      Based on
  37   37   *              acosh(x) = log [ x + sqrt(x*x-1) ]
  38   38   *      we have
  39   39   *              acosh(x) := log(x)+ln2, if x is large; else
  40   40   *              acosh(x) := log(2x-1/(sqrt(x*x-1)+x)) if x > 2; else
  41   41   *              acosh(x) := log1p(t+sqrt(2.0*t+t*t)); where t = x-1.
  42   42   *
  43   43   * Special cases:
  44   44   *      acosh(x) is NaN with signal if x < 1.
  45   45   *      acosh(NaN) is NaN without signal.
  46   46   */
  47   47  /* INDENT ON */
  48   48  
  49      -#include "libm_synonyms.h"      /* __acosh, __log, __log1p */
  50   49  #include "libm_protos.h"        /* _SVID_libm_error */
  51   50  #include "libm_macros.h"
  52   51  #include <math.h>
  53   52  
  54   53  static const double
  55   54          one = 1.0,
  56   55          ln2 = 6.93147180559945286227e-01;       /* 3FE62E42, FEFA39EF */
  57   56  
  58   57  double
  59   58  acosh(double x) {

  60   59          double t;
  61   60          int hx;
  62   61  
  63   62          hx = ((int *) &x)[HIWORD];
  64   63          if (hx < 0x3ff00000) {  /* x < 1 */
  65   64                  if (isnan(x))
  66   65  #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
  67   66                          return (hx >= 0xfff80000 ? x : (x - x) / (x - x));
  68   67                          /* assumes sparc-like QNaN */
  69   68  #else
  70   69                          return (x - x) / (x - x);
  71   70  #endif
  72   71                  else
  73   72                          return (_SVID_libm_err(x, x, 29));
  74   73          } else if (hx >= 0x41b00000) {
  75   74                  /* x > 2**28 */
  76   75                  if (hx >= 0x7ff00000) { /* x is inf of NaN */
  77   76  #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
  78   77                          return (hx >= 0x7ff80000 ? x : x + x);
  79   78                          /* assumes sparc-like QNaN */
  80   79  #else
  81   80                          return (x + x);
  82   81  #endif
  83   82                  } else  /* acosh(huge)=log(2x) */
  84   83                          return (log(x) + ln2);
  85   84          } else if (((hx - 0x3ff00000) | ((int *) &x)[LOWORD]) == 0) {
  86   85                  return (0.0);   /* acosh(1) = 0 */
  87   86          } else if (hx > 0x40000000) {
  88   87                  /* 2**28 > x > 2 */
  89   88                  t = x * x;
  90   89                  return (log(2.0 * x - one / (x + sqrt(t - one))));
  91   90          } else {
  92   91                  /* 1 < x < 2 */
  93   92                  t = x - one;
  94   93                  return (log1p(t + sqrt(2.0 * t + t * t)));
  95   94          }
  96   95  }

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