1 /* e_coshf.c -- float version of e_cosh.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, half=0.5, huge = 1.0e30; 20 21 float 22 coshf(float x) 23 { 24 float t,w; 25 int32_t ix; 26 27 GET_FLOAT_WORD(ix,x); 28 ix &= 0x7fffffff; 29 30 /* x is INF or NaN */ 31 if(ix>=0x7f800000) return x*x; 32 33 /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */ 34 if(ix<0x3eb17218) { 35 t = expm1f(fabsf(x)); 36 w = one+t; 37 if (ix<0x39800000) return one; /* cosh(tiny) = 1 */ 38 return one+(t*t)/(w+w); 39 } 40 41 /* |x| in [0.5*ln2,9], return (exp(|x|)+1/exp(|x|))/2; */ 42 if (ix < 0x41100000) { 43 t = expf(fabsf(x)); 44 return half*t+half/t; 45 } 46 47 /* |x| in [9, log(maxfloat)] return half*exp(|x|) */ 48 if (ix < 0x42b17217) return half*expf(fabsf(x)); 49 50 /* |x| in [log(maxfloat), overflowthresold] */ 51 if (ix<=0x42b2d4fc) 52 return __ldexp_expf(fabsf(x), -1); 53 54 /* |x| > overflowthresold, cosh(x) overflow */ 55 return huge*huge; 56 } 57