11dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project/* s_tanhf.c -- float version of s_tanh.c. 21dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 31dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project */ 41dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 51dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project/* 61dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * ==================================================== 71dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 81dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 91dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * Developed at SunPro, a Sun Microsystems, Inc. business. 101dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * Permission to use, copy, modify, and distribute this 111dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * software is freely granted, provided that this notice 121dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * is preserved. 131dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * ==================================================== 141dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project */ 151dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 16a0ee07829a9ba7e99ef68e8c12551301cc797f0fElliott Hughes#include <sys/cdefs.h> 17a0ee07829a9ba7e99ef68e8c12551301cc797f0fElliott Hughes__FBSDID("$FreeBSD$"); 181dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 191dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project#include "math.h" 201dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project#include "math_private.h" 211dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 221dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Projectstatic const float one=1.0, two=2.0, tiny = 1.0e-30, huge = 1.0e30; 231dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Projectfloat 241dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Projecttanhf(float x) 251dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project{ 261dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project float t,z; 271dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project int32_t jx,ix; 281dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 291dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project GET_FLOAT_WORD(jx,x); 301dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project ix = jx&0x7fffffff; 311dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 321dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project /* x is INF or NaN */ 331dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project if(ix>=0x7f800000) { 341dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project if (jx>=0) return one/x+one; /* tanh(+-inf)=+-1 */ 351dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project else return one/x-one; /* tanh(NaN) = NaN */ 361dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project } 371dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 381dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project /* |x| < 9 */ 391dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project if (ix < 0x41100000) { /* |x|<9 */ 401dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project if (ix<0x39800000) { /* |x|<2**-12 */ 411dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project if(huge+x>one) return x; /* tanh(tiny) = tiny with inexact */ 421dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project } 431dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project if (ix>=0x3f800000) { /* |x|>=1 */ 441dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project t = expm1f(two*fabsf(x)); 451dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project z = one - two/(t+two); 461dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project } else { 471dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project t = expm1f(-two*fabsf(x)); 481dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project z= -t/(t+two); 491dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project } 501dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project /* |x| >= 9, return +-1 */ 511dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project } else { 521dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project z = one - tiny; /* raise inexact flag */ 531dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project } 541dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project return (jx>=0)? z: -z; 551dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 56