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/cosh.c
          +++ new/usr/src/lib/libm/common/C/cosh.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   * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  23   23   */
  24   24  /*
  25   25   * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
  26   26   * Use is subject to license terms.
  27   27   */
  28   28  
  29      -#pragma weak cosh = __cosh
       29 +#pragma weak __cosh = cosh
  30   30  
  31   31  /* INDENT OFF */
  32   32  /*
  33   33   * cosh(x)
  34   34   * Code originated from 4.3bsd.
  35   35   * Modified by K.C. Ng for SUN 4.0 libm.
  36   36   * Method :
  37   37   *      1. Replace x by |x| (cosh(x) = cosh(-x)).
  38   38   *      2.
  39   39   *                                       [ exp(x) - 1 ]^2

  40   40   *  0        <= x <= 0.3465  :  cosh(x) := 1 + -------------------
  41   41   *                                                                    2*exp(x)
  42   42   *
  43   43   *                                                 exp(x) +  1/exp(x)
  44   44   *  0.3465   <= x <= 22      :  cosh(x) := -------------------
  45   45   *                                                                         2
  46   46   *  22       <= x <= lnovft  :  cosh(x) := exp(x)/2
  47   47   *  lnovft   <= x <  INF     :  cosh(x) := scalbn(exp(x-1024*ln2),1023)
  48   48   *
  49   49   *      Note: .3465 is a number near one half of ln2.
  50   50   *
  51   51   * Special cases:
  52   52   *      cosh(x) is |x| if x is +INF, -INF, or NaN.
  53   53   *      only cosh(0)=1 is exact for finite x.
  54   54   */
  55   55  /* INDENT ON */
  56   56  
  57   57  #include "libm.h"
  58   58  
  59   59  static const double
  60   60          ln2 = 6.93147180559945286227e-01,
  61   61          ln2hi = 6.93147180369123816490e-01,
  62   62          ln2lo = 1.90821492927058770002e-10,
  63   63          lnovft = 7.09782712893383973096e+02;
  64   64  
  65   65  double
  66   66  cosh(double x) {
  67   67          double t, w;
  68   68  
  69   69          w = fabs(x);
  70   70          if (!finite(w))
  71   71                  return (w * w);
  72   72          if (w < 0.3465) {
  73   73                  t = expm1(w);
  74   74                  w = 1.0 + t;
  75   75                  if (w != 1.0)
  76   76                          w = 1.0 + (t * t) / (w + w);
  77   77                  return (w);
  78   78          } else if (w < 22.0) {
  79   79                  t = exp(w);
  80   80                  return (0.5 * (t + 1.0 / t));
  81   81          } else if (w <= lnovft) {
  82   82                  return (0.5 * exp(w));
  83   83          } else {
  84   84                  w = (w - 1024 * ln2hi) - 1024 * ln2lo;
  85   85                  if (w >= ln2)
  86   86                          return (_SVID_libm_err(x, x, 5));
  87   87                  else
  88   88                          return (scalbn(exp(w), 1023));
  89   89          }
  90   90  }

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