1 /* e_acoshf.c -- float version of e_acosh.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 #ifndef lint 17 static char rcsid[] = "$Id: e_acoshf.c,v 1.1.1.1 1994/08/19 09:39:44 jkh Exp $"; 18 #endif 19 20 #include "math.h" 21 #include "math_private.h" 22 23 #ifdef __STDC__ 24 static const float 25 #else 26 static float 27 #endif 28 one = 1.0, 29 ln2 = 6.9314718246e-01; /* 0x3f317218 */ 30 31 #ifdef __STDC__ 32 float __ieee754_acoshf(float x) 33 #else 34 float __ieee754_acoshf(x) 35 float x; 36 #endif 37 { 38 float t; 39 int32_t hx; 40 GET_FLOAT_WORD(hx,x); 41 if(hx<0x3f800000) { /* x < 1 */ 42 return (x-x)/(x-x); 43 } else if(hx >=0x4d800000) { /* x > 2**28 */ 44 if(hx >=0x7f800000) { /* x is inf of NaN */ 45 return x+x; 46 } else 47 return __ieee754_logf(x)+ln2; /* acosh(huge)=log(2x) */ 48 } else if (hx==0x3f800000) { 49 return 0.0; /* acosh(1) = 0 */ 50 } else if (hx > 0x40000000) { /* 2**28 > x > 2 */ 51 t=x*x; 52 return __ieee754_logf((float)2.0*x-one/(x+sqrtf(t-one))); 53 } else { /* 1<x<2 */ 54 t = x-one; 55 return log1pf(t+sqrtf((float)2.0*t+t*t)); 56 } 57 } 58