--- old/usr/src/lib/libm/common/Q/tanhl.c
          +++ new/usr/src/lib/libm/common/Q/tanhl.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   30  #if defined(ELFOBJ)
  31   31  #pragma weak tanhl = __tanhl
  32   32  #endif
  33   33  
  34   34  /*
  35   35   * tanhl(x) returns the hyperbolic tangent of x
  36   36   *
  37   37   * Method :
  38   38   *      1. reduce x to non-negative:  tanhl(-x) = - tanhl(x).
  39   39   *      2.
  40   40   *        0      <  x <=  small    :  tanhl(x) := x
  41   41   *                                                -expm1l(-2x)
  42   42   *        small  <  x <=  1        :  tanhl(x) := --------------
  43   43   *                                               expm1l(-2x) + 2
  44   44   *                                                        2
  45   45   *        1      <= x <= threshold :  tanhl(x) := 1 -  ---------------
  46   46   *                                                    expm1l(2x) + 2
  47   47   *     threshold <  x <= INF       :  tanhl(x) := 1.
  48   48   *
  49   49   * where
  50   50   *      single :        small = 1.e-5           threshold = 11.0
  51   51   *      double :        small = 1.e-10          threshold = 22.0
  52   52   *      quad   :        small = 1.e-20          threshold = 45.0
  53   53   *
  54   54   * Note: threshold was chosen so that
  55   55   *              fl(1.0+2/(expm1(2*threshold)+2)) == 1.
  56   56   *
  57   57   * Special cases:
  58   58   *      tanhl(NaN) is NaN;
  59   59   *      only tanhl(0.0)=0.0 is exact for finite argument.
  60   60   */
  61   61  
  62   62  #include "libm.h"
  63   63  #include "longdouble.h"
  64   64  

  65   65  static const long double small = 1.0e-20L, one = 1.0, two = 2.0,
  66   66  #ifndef lint
  67   67          big = 1.0e+20L,
  68   68  #endif
  69   69          threshold = 45.0L;
  70   70  
  71   71  long double
  72   72  tanhl(long double x) {
  73   73          long double t, y, z;
  74   74          int signx;
       75 +        volatile long double dummy;
  75   76  
  76   77          if (isnanl(x))
  77   78                  return (x + x);         /* x is NaN */
  78   79          signx = signbitl(x);
  79   80          t = fabsl(x);
  80   81          z = one;
  81   82          if (t <= threshold) {
  82   83                  if (t > one)
  83   84                          z = one - two / (expm1l(t + t) + two);
  84   85                  else if (t > small) {
  85   86                          y = expm1l(-t - t);
  86   87                          z = -y / (y + two);
  87   88                  } else {
  88   89  #ifndef lint
  89      -                        volatile long double dummy = t + big;
       90 +                        dummy = t + big;
  90   91                                                          /* inexact if t != 0 */
  91   92  #endif
  92   93                          return (x);
  93   94                  }
  94   95          } else if (!finitel(t))
  95   96                  return (copysignl(one, x));
  96   97          else
  97   98                  return (signx ? -z + small * small : z - small * small);
  98   99          return (signx ? -z : z);
  99  100  }
    

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