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/* Copyright (C) 1996 Olaf Flebbe
O.Flebbe@science-computing.uni-tuebingen.de
This file is part of the Linux C Library.
The Linux C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The Linux C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details. */
/*
Idea by John C. Bowman (bowman@hagar.ph.utexas.edu).
*/
#include <math.h>
double asinh(const double x)
{
double arg = x, y=fabs(arg);
if ( y > 1e30) {
/*
Make sure y*y does not overflow; difference is beyond
machine precision
*/
return copysign( M_LN2 + log( y), x);
} else {
double z=y*y;
return copysign( log1p( z/(sqrt(z+1.0)+1.0)+y), x);
}
}
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