1 /* s_tanhf.c -- float version of s_tanh.c. 2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 3 */ 4 5 /* 6 * ==================================================== 7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 8 * 9 * Developed at SunPro, a Sun Microsystems, Inc. business. 10 * Permission to use, copy, modify, and distribute this 11 * software is freely granted, provided that this notice 12 * is preserved. 13 * ==================================================== 14 */ 15 16 #include "cdefs-compat.h" 17 //__FBSDID("$FreeBSD: src/lib/msun/src/s_tanhf.c,v 1.9 2008/02/22 02:30:36 das Exp $"); 18 19 #include <openlibm.h> 20 21 #include "math_private.h" 22 23 static const float one=1.0, two=2.0, tiny = 1.0e-30, huge = 1.0e30; 24 DLLEXPORT float 25 tanhf(float x) 26 { 27 float t,z; 28 int32_t jx,ix; 29 30 GET_FLOAT_WORD(jx,x); 31 ix = jx&0x7fffffff; 32 33 /* x is INF or NaN */ 34 if(ix>=0x7f800000) { 35 if (jx>=0) return one/x+one; /* tanh(+-inf)=+-1 */ 36 else return one/x-one; /* tanh(NaN) = NaN */ 37 } 38 39 /* |x| < 9 */ 40 if (ix < 0x41100000) { /* |x|<9 */ 41 if (ix<0x39800000) { /* |x|<2**-12 */ 42 if(huge+x>one) return x; /* tanh(tiny) = tiny with inexact */ 43 } 44 if (ix>=0x3f800000) { /* |x|>=1 */ 45 t = expm1f(two*fabsf(x)); 46 z = one - two/(t+two); 47 } else { 48 t = expm1f(-two*fabsf(x)); 49 z= -t/(t+two); 50 } 51 /* |x| >= 9, return +-1 */ 52 } else { 53 z = one - tiny; /* raise inexact flag */ 54 } 55 return (jx>=0)? z: -z; 56 } 57