| 1 | /* e_acoshf.c -- float version of e_acosh.c. |
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| 2 | */ |
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| 3 | |
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| 4 | /* |
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| 5 | * ==================================================== |
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| 6 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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| 7 | * |
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| 8 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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| 9 | * Permission to use, copy, modify, and distribute this |
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| 10 | * software is freely granted, provided that this notice |
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| 11 | * is preserved. |
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| 12 | * ==================================================== |
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| 13 | */ |
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| 14 | |
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| 15 | #if defined(LIBM_SCCS) && !defined(lint) |
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| 16 | static char rcsid[] = "$NetBSD: e_acoshf.c,v 1.5 1995/05/12 04:57:20 jtc Exp $" ; |
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| 17 | #endif |
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| 18 | |
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| 19 | #include <math.h> |
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| 20 | #include <math_private.h> |
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| 21 | #include <libm-alias-finite.h> |
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| 22 | |
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| 23 | static const float |
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| 24 | one = 1.0, |
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| 25 | ln2 = 6.9314718246e-01; /* 0x3f317218 */ |
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| 26 | |
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| 27 | float __ieee754_acoshf(float x) |
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| 28 | { |
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| 29 | float t; |
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| 30 | int32_t hx; |
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| 31 | GET_FLOAT_WORD(hx,x); |
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| 32 | if(hx<0x3f800000) { /* x < 1 */ |
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| 33 | return (x-x)/(x-x); |
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| 34 | } else if(hx >=0x4d800000) { /* x > 2**28 */ |
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| 35 | if(hx >=0x7f800000) { /* x is inf of NaN */ |
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| 36 | return x+x; |
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| 37 | } else |
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| 38 | return __ieee754_logf(x)+ln2; /* acosh(huge)=log(2x) */ |
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| 39 | } else if (hx==0x3f800000) { |
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| 40 | return 0.0; /* acosh(1) = 0 */ |
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| 41 | } else if (hx > 0x40000000) { /* 2**28 > x > 2 */ |
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| 42 | t=x*x; |
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| 43 | return __ieee754_logf((float)2.0*x-one/(x+sqrtf(t-one))); |
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| 44 | } else { /* 1<x<2 */ |
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| 45 | t = x-one; |
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| 46 | return __log1pf(x: t+sqrtf((float)2.0*t+t*t)); |
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| 47 | } |
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| 48 | } |
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| 49 | libm_alias_finite (__ieee754_acoshf, __acoshf) |
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| 50 | |
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