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| [1] | 1 | |
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| 2 | /* @(#)w_gamma.c 5.1 93/09/24 */ |
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| 3 | /* |
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| 4 | * ==================================================== |
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| 5 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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| 6 | * |
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| 7 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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| 8 | * Permission to use, copy, modify, and distribute this |
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| 9 | * software is freely granted, provided that this notice |
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| 10 | * is preserved. |
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| 11 | * ==================================================== |
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| 12 | * |
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| 13 | */ |
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| 14 | |
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| 15 | /* double gamma(double x) |
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| 16 | * Return the logarithm of the Gamma function of x. |
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| 17 | * |
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| 18 | * Method: call gamma_r |
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| 19 | */ |
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| 20 | |
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| 21 | #include <libm/fdlibm.h> |
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| 22 | |
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| 23 | //extern int signgam; |
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| 24 | |
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| 25 | #ifdef __STDC__ |
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| 26 | double gamma(double x) |
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| 27 | #else |
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| 28 | double gamma(x) |
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| 29 | double x; |
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| 30 | #endif |
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| 31 | { |
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| 32 | #ifdef _IEEE_LIBM |
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| 33 | return __ieee754_gamma_r(x,&signgam); |
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| 34 | #else |
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| 35 | double y; |
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| 36 | y = __ieee754_gamma_r(x,&signgam); |
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| 37 | if(_LIB_VERSION == _IEEE_) return y; |
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| 38 | if(!finite(y)&&finite(x)) { |
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| 39 | if(floor(x)==x&&x<=0.0) |
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| 40 | return __kernel_standard(x,x,41); /* gamma pole */ |
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| 41 | else |
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| 42 | return __kernel_standard(x,x,40); /* gamma overflow */ |
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| 43 | } else |
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| 44 | return y; |
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| 45 | #endif |
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| 46 | } |
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