mingw-w64-crt/math/softmath/asinl.c

/*
 This Software is provided under the Zope Public License (ZPL) Version 2.1.

 Copyright (c) 2014 by the mingw-w64 project

 See the AUTHORS file for the list of contributors to the mingw-w64 project.

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 as GPL compatible by the Free Software Foundation (FSF).

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 modification, are permitted provided that the following conditions are met:

   1. Redistributions in source code must retain the accompanying copyright
      notice, this list of conditions, and the following disclaimer.
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      copyright notice, this list of conditions, and the following disclaimer
      in the documentation and/or other materials provided with the
      distribution.
   3. Names of the copyright holders must not be used to endorse or promote
      products derived from this software without prior written permission
      from the copyright holders.
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      not give you the right to use Servicemarks (sm) or Trademarks (tm) of
      the copyright holders.  Use of them is covered by separate agreement
      with the copyright holders.
   5. If any files are modified, you must cause the modified files to carry
      prominent notices stating that you changed the files and the date of
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 Disclaimer

 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY EXPRESSED
 OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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*/

#include "softmath_private.h"

long double asinl(long double x)
{
#if defined(__arm__) || defined(_ARM_)
    double result = 0.0;
    int n, aprox = 12;

    if (x > 1.0 || x < -1.0)
        return NAN;

    if      (x > 0.95)  aprox *= 8;
    else if (x > 0.9)   aprox *= 4;
    else if (x > 0.8)   aprox *= 2;

    for(n = 0; n < aprox; n++)
    {
        double n2ff = bsd__ieee754_pow(2, n) * softmath_fact(n);
        result += (softmath_fact(2 * n) / (n2ff * n2ff)) * (bsd__ieee754_pow(x, ((2 * n) + 1)) / ((2 * n) + 1));
    }

    return result;
#else
#error Not supported on your platform yet
#endif
}