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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 4973 | right-hear | 1 | /* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */ |
| 2 | /* e_coshf.c -- float version of e_cosh.c. |
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| 3 | * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. |
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| 4 | */ |
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| 5 | |||
| 6 | /* |
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| 7 | * ==================================================== |
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| 8 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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| 9 | * |
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| 10 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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| 11 | * Permission to use, copy, modify, and distribute this |
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| 12 | * software is freely granted, provided that this notice |
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| 13 | * is preserved. |
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| 14 | * ==================================================== |
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| 15 | */ |
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| 16 | |||
| 17 | #if defined(LIBM_SCCS) && !defined(lint) |
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| 18 | static char rcsid[] = "$Id: e_coshf.c,v 1.2 1994/08/18 23:05:17 jtc Exp $"; |
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| 19 | #endif |
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| 20 | |||
| 21 | #include "math.h" |
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| 22 | #include "math_private.h" |
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| 23 | |||
| 24 | #ifdef __STDC__ |
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| 25 | static const float one = 1.0, half=0.5, huge = 1.0e30; |
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| 26 | #else |
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| 27 | static float one = 1.0, half=0.5, huge = 1.0e30; |
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| 28 | #endif |
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| 29 | |||
| 30 | #ifdef __STDC__ |
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| 31 | float __ieee754_coshf(float x) |
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| 32 | #else |
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| 33 | float __ieee754_coshf(x) |
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| 34 | float x; |
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| 35 | #endif |
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| 36 | { |
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| 37 | float t,w; |
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| 38 | int32_t ix; |
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| 39 | |||
| 40 | GET_FLOAT_WORD(ix,x); |
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| 41 | ix &= 0x7fffffff; |
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| 42 | |||
| 43 | /* x is INF or NaN */ |
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| 44 | if(ix>=0x7f800000) return x*x; |
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| 45 | |||
| 46 | /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */ |
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| 47 | if(ix<0x3eb17218) { |
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| 48 | t = expm1f(fabsf(x)); |
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| 49 | w = one+t; |
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| 50 | if (ix<0x24000000) return w; /* cosh(tiny) = 1 */ |
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| 51 | return one+(t*t)/(w+w); |
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| 52 | } |
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| 53 | |||
| 54 | /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */ |
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| 55 | if (ix < 0x41b00000) { |
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| 56 | t = __ieee754_expf(fabsf(x)); |
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| 57 | return half*t+half/t; |
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| 58 | } |
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| 59 | |||
| 60 | /* |x| in [22, log(maxdouble)] return half*exp(|x|) */ |
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| 61 | if (ix < 0x42b17180) return half*__ieee754_expf(fabsf(x)); |
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| 62 | |||
| 63 | /* |x| in [log(maxdouble), overflowthresold] */ |
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| 64 | if (ix<=0x42b2d4fc) { |
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| 65 | w = __ieee754_expf(half*fabsf(x)); |
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| 66 | t = half*w; |
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| 67 | return t*w; |
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| 68 | } |
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| 69 | |||
| 70 | /* |x| > overflowthresold, cosh(x) overflow */ |
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| 71 | return huge*huge; |
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| 72 | } |