asinh.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 54 行

/****************************************************************************
*
*                            Open Watcom Project
*
*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
*
*  ========================================================================
*
*    This file contains Original Code and/or Modifications of Original
*    Code as defined in and that are subject to the Sybase Open Watcom
*    Public License version 1.0 (the 'License'). You may not use this file
*    except in compliance with the License. BY USING THIS FILE YOU AGREE TO
*    ALL TERMS AND CONDITIONS OF THE LICENSE. A copy of the License is
*    provided with the Original Code and Modifications, and is also
*    available at www.sybase.com/developer/opensource.
*
*    The Original Code and all software distributed under the License are
*    distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
*    EXPRESS OR IMPLIED, AND SYBASE AND ALL CONTRIBUTORS HEREBY DISCLAIM
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*    NON-INFRINGEMENT. Please see the License for the specific language
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*  ========================================================================
*
* Description:  Hyperbolic arcsine routine.
*
****************************************************************************/


#include "variety.h"
#include <math.h>
#include "ifprag.h"

//      asinh(x) = log( x + sqrt(x*x + 1.0) );

_WMRTLINK double __asinh( double x )
{
    return( asinh( x ) );
}

_WMRTLINK double asinh( double x )
/********************************/
{
    double  z;

    z = x + sqrt( x * x + 1.0 );
    if( z == 0.0 ) {
        return( -HUGE_VAL );
    }
    return( log( z ) );
}