1 /* e_atanhf.c -- float version of e_atanh.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 "math.h" 17 #include "math_private.h" 18 19 static const float one = 1.0, huge = 1e30; 20 21 static const float zero = 0.0; 22 23 float 24 atanhf(float x) 25 { 26 float t; 27 int32_t hx,ix; 28 GET_FLOAT_WORD(hx,x); 29 ix = hx&0x7fffffff; 30 if (ix>0x3f800000) /* |x|>1 */ 31 return (x-x)/(x-x); 32 if(ix==0x3f800000) 33 return x/zero; 34 if(ix<0x31800000&&(huge+x)>zero) return x; /* x<2**-28 */ 35 SET_FLOAT_WORD(x,ix); 36 if(ix<0x3f000000) { /* x < 0.5 */ 37 t = x+x; 38 t = (float)0.5*log1pf(t+t*x/(one-x)); 39 } else 40 t = (float)0.5*log1pf((x+x)/(one-x)); 41 if(hx>=0) return t; else return -t; 42 } 43