relibc_openlibm/src/e_atanhf.c

/* e_atanhf.c -- float version of e_atanh.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 */

/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

#include "cdefs-compat.h"
//__FBSDID("$FreeBSD: src/lib/msun/src/e_atanhf.c,v 1.7 2008/02/22 02:30:34 das Exp $");

#include <openlibm_math.h>

#include "math_private.h"

static const float one = 1.0, huge = 1e30;

static const float zero = 0.0;

OLM_DLLEXPORT float
__ieee754_atanhf(float x)
{
	float t;
	int32_t hx,ix;
	GET_FLOAT_WORD(hx,x);
	ix = hx&0x7fffffff;
	if (ix>0x3f800000) 		/* |x|>1 */
	    return (x-x)/(x-x);
	if(ix==0x3f800000)
	    return x/zero;
	if(ix<0x31800000&&(huge+x)>zero) return x;	/* x<2**-28 */
	SET_FLOAT_WORD(x,ix);
	if(ix<0x3f000000) {		/* x < 0.5 */
	    t = x+x;
	    t = (float)0.5*log1pf(t+t*x/(one-x));
	} else
	    t = (float)0.5*log1pf((x+x)/(one-x));
	if(hx>=0) return t; else return -t;
}