1 | |
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2 | /* @(#)w_lgamma.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 lgamma(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 __ieee754_lgamma_r |
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19 | */ |
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20 | |
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21 | #include "fdlibm.h" |
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22 | #include <reent.h> |
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23 | #include <errno.h> |
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24 | |
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25 | #ifndef _DOUBLE_IS_32BITS |
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26 | |
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27 | #ifdef __STDC__ |
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28 | double lgamma(double x) |
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29 | #else |
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30 | double lgamma(x) |
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31 | double x; |
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32 | #endif |
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33 | { |
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34 | #ifdef _IEEE_LIBM |
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35 | return __ieee754_lgamma_r(x,&(_REENT_SIGNGAM(_REENT))); |
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36 | #else |
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37 | double y; |
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38 | struct exception exc; |
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39 | y = __ieee754_lgamma_r(x,&(_REENT_SIGNGAM(_REENT))); |
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40 | if(_LIB_VERSION == _IEEE_) return y; |
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41 | if(!finite(y)&&finite(x)) { |
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42 | #ifndef HUGE_VAL |
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43 | #define HUGE_VAL inf |
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44 | double inf = 0.0; |
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45 | |
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46 | SET_HIGH_WORD(inf,0x7ff00000); /* set inf to infinite */ |
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47 | #endif |
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48 | exc.name = "lgamma"; |
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49 | exc.err = 0; |
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50 | exc.arg1 = x; |
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51 | exc.arg2 = x; |
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52 | if (_LIB_VERSION == _SVID_) |
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53 | exc.retval = HUGE; |
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54 | else |
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55 | exc.retval = HUGE_VAL; |
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56 | if(floor(x)==x&&x<=0.0) { |
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57 | /* lgamma(-integer) */ |
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58 | exc.type = SING; |
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59 | if (_LIB_VERSION == _POSIX_) |
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60 | errno = EDOM; |
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61 | else if (!matherr(&exc)) { |
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62 | errno = EDOM; |
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63 | } |
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64 | |
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65 | } else { |
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66 | /* lgamma(finite) overflow */ |
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67 | exc.type = OVERFLOW; |
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68 | if (_LIB_VERSION == _POSIX_) |
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69 | errno = ERANGE; |
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70 | else if (!matherr(&exc)) { |
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71 | errno = ERANGE; |
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72 | } |
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73 | } |
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74 | if (exc.err != 0) |
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75 | errno = exc.err; |
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76 | return exc.retval; |
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77 | } else |
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78 | return y; |
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79 | #endif |
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80 | } |
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81 | |
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82 | #endif /* defined(_DOUBLE_IS_32BITS) */ |
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83 | |
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84 | |
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85 | |
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86 | |
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87 | |
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88 | |
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89 | |
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