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 #include <sys/cdefs.h> 17 #include "math.h" 18 #include "math_private.h" 19 20 static const float 21 one = 1.0, 22 ln2 = 6.9314718246e-01; /* 0x3f317218 */ 23 24 float 25 acoshf(float x) 26 { 27 float t; 28 int32_t hx; 29 GET_FLOAT_WORD(hx,x); 30 if(hx<0x3f800000) { /* x < 1 */ 31 return (x-x)/(x-x); 32 } else if(hx >=0x4d800000) { /* x > 2**28 */ 33 if(hx >=0x7f800000) { /* x is inf of NaN */ 34 return x+x; 35 } else 36 return logf(x)+ln2; /* acosh(huge)=log(2x) */ 37 } else if (hx==0x3f800000) { 38 return 0.0; /* acosh(1) = 0 */ 39 } else if (hx > 0x40000000) { /* 2**28 > x > 2 */ 40 t=x*x; 41 return logf((float)2.0*x-one/(x+sqrtf(t-one))); 42 } else { /* 1<x<2 */ 43 t = x-one; 44 return log1pf(t+sqrtf((float)2.0*t+t*t)); 45 } 46 } 47