1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
|
/* gdtrf.c
*
* Gamma distribution function
*
*
*
* SYNOPSIS:
*
* float a, b, x, y, gdtrf();
*
* y = gdtrf( a, b, x );
*
*
*
* DESCRIPTION:
*
* Returns the integral from zero to x of the gamma probability
* density function:
*
*
* x
* b -
* a | | b-1 -at
* y = ----- | t e dt
* - | |
* | (b) -
* 0
*
* The incomplete gamma integral is used, according to the
* relation
*
* y = igam( b, ax ).
*
*
* ACCURACY:
*
* Relative error:
* arithmetic domain # trials peak rms
* IEEE 0,100 5000 5.8e-5 3.0e-6
*
* ERROR MESSAGES:
*
* message condition value returned
* gdtrf domain x < 0 0.0
*
*/
/* gdtrcf.c
*
* Complemented gamma distribution function
*
*
*
* SYNOPSIS:
*
* float a, b, x, y, gdtrcf();
*
* y = gdtrcf( a, b, x );
*
*
*
* DESCRIPTION:
*
* Returns the integral from x to infinity of the gamma
* probability density function:
*
*
* inf.
* b -
* a | | b-1 -at
* y = ----- | t e dt
* - | |
* | (b) -
* x
*
* The incomplete gamma integral is used, according to the
* relation
*
* y = igamc( b, ax ).
*
*
* ACCURACY:
*
* Relative error:
* arithmetic domain # trials peak rms
* IEEE 0,100 5000 9.1e-5 1.5e-5
*
* ERROR MESSAGES:
*
* message condition value returned
* gdtrcf domain x < 0 0.0
*
*/
/* gdtr() */
/*
Cephes Math Library Release 2.2: July, 1992
Copyright 1984, 1987, 1992 by Stephen L. Moshier
Direct inquiries to 30 Frost Street, Cambridge, MA 02140
*/
#include <math.h>
#ifdef ANSIC
float igamf(float, float), igamcf(float, float);
#else
float igamf(), igamcf();
#endif
float gdtrf( float aa, float bb, float xx )
{
float a, b, x;
a = aa;
b = bb;
x = xx;
if( x < 0.0 )
{
mtherr( "gdtrf", DOMAIN );
return( 0.0 );
}
return( igamf( b, a * x ) );
}
float gdtrcf( float aa, float bb, float xx )
{
float a, b, x;
a = aa;
b = bb;
x = xx;
if( x < 0.0 )
{
mtherr( "gdtrcf", DOMAIN );
return( 0.0 );
}
return( igamcf( b, a * x ) );
}
|
