/* s_tanhf.c -- float version of s_tanh.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.

 * ====================================================

 */

#if defined(LIBM_SCCS) && !defined(lint)

static char rcsid[] = "$NetBSD: s_tanhf.c,v 1.4 1995/05/10 20:48:24 jtc Exp $";

#endif

#include <float.h>

#include <math.h>

#include <math_private.h>

#include <math-underflow.h>

#include <libm-alias-float.h>

static const float one=1.0, two=2.0, tiny = 1.0e-30;

float __tanhf(float x)

{

	float t,z;

	int32_t jx,ix;

	GET_FLOAT_WORD(jx,x);

	ix = jx&0x7fffffff;

    /* x is INF or NaN */

	if(ix>=0x7f800000) {

	    if (jx>=0) return one/x+one;    /* tanh(+-inf)=+-1 */

	    else       return one/x-one;    /* tanh(NaN) = NaN */

	}

    /* |x| < 22 */

	if (ix < 0x41b00000) {		/* |x|<22 */

	    if (ix == 0)

		return x;		/* x == +-0 */

	    if (ix<0x24000000) 		/* |x|<2**-55 */

	      {

		math_check_force_underflow (x);

		return x*(one+x);    	/* tanh(small) = small */

	      }

	    if (ix>=0x3f800000) {	/* |x|>=1  */

		t = __expm1f(two*fabsf(x));

		z = one - two/(t+two);

	    } else {

	        t = __expm1f(-two*fabsf(x));

	        z= -t/(t+two);

	    }

    /* |x| > 22, return +-1 */

	} else {

	    z = one - tiny;		/* raised inexact flag */

	}

	return (jx>=0)? z: -z;

}

libm_alias_float (__tanh, tanh)