text: /* 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 "math.h"
  #include "math_private.h"
  
  #ifdef __STDC__
  static const float one=1.0, two=2.0, tiny = 1.0e-30;
  #else
  static float one=1.0, two=2.0, tiny = 1.0e-30;
  #endif
  
  #ifdef __STDC__
  	float tanhf(float x)
  #else
  	float tanhf(x)
  	float x;
  #endif
  {
  	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<0x24000000) 		/* |x|<2**-55 */
  		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;
  }
  