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/Q/acosl.c
          +++ new/usr/src/lib/libm/common/Q/acosl.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  /*
  31   31   * arccosin function
  32   32   *                            ________
  33   33   *                           / 1 - x
  34   34   *      acos(x) = 2*atan2(  / -------- , 1 )
  35   35   *                        \/   1 + x
  36   36   *

  37   37   *                            ________
  38   38   *                           / 1 - x
  39   39   *              = 2*atan (  / -------- ) for non-exceptional x.
  40   40   *                        \/   1 + x
  41   41   *
  42   42   * Special cases:
  43   43   *      if x is NaN, return x itself;
  44   44   *      if |x|>1, return NaN with invalid signal.
  45   45   */
  46   46  
  47      -#pragma weak acosl = __acosl
       47 +#pragma weak __acosl = acosl
  48   48  
  49   49  #include "libm.h"
  50   50  
  51   51  static const long double zero = 0.0L, one = 1.0L;
  52   52  
  53   53  long double
  54   54  acosl(long double x) {
  55   55          if (isnanl(x))
  56   56                  return (x + x);
  57   57          else if (fabsl(x) < one)
  58   58                  x = atanl(sqrtl((one - x) / (one + x)));
  59   59          else if (x == -one)
  60   60                  x = atan2l(one, zero);  /* x <- PI */
  61   61          else if (x == one)
  62   62                  x = zero;
  63   63          else {          /* |x| > 1  create invalid signal */
  64   64                  return (zero / zero);
  65   65          }
  66   66          return (x + x);
  67   67  }
    

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