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
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
|
/* histogram/pdf2d.c
*
* Copyright (C) 1996, 1997, 1998, 1999, 2000 Brian Gough
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <config.h>
#include <stdlib.h>
#include <gsl/gsl_errno.h>
#include <gsl/gsl_histogram.h>
#include <gsl/gsl_histogram2d.h>
#include "find.c"
int
gsl_histogram2d_pdf_sample (const gsl_histogram2d_pdf * p,
double r1, double r2,
double *x, double *y)
{
size_t k;
int status;
/* Wrap the exclusive top of the bin down to the inclusive bottom of
the bin. Since this is a single point it should not affect the
distribution. */
if (r2 == 1.0)
{
r2 = 0.0;
}
if (r1 == 1.0)
{
r1 = 0.0;
}
status = find (p->nx * p->ny, p->sum, r1, &k);
if (status)
{
GSL_ERROR ("cannot find r1 in cumulative pdf", GSL_EDOM);
}
else
{
size_t i = k / p->ny;
size_t j = k - (i * p->ny);
double delta = (r1 - p->sum[k]) / (p->sum[k + 1] - p->sum[k]);
*x = p->xrange[i] + delta * (p->xrange[i + 1] - p->xrange[i]);
*y = p->yrange[j] + r2 * (p->yrange[j + 1] - p->yrange[j]);
return GSL_SUCCESS;
}
}
gsl_histogram2d_pdf *
gsl_histogram2d_pdf_alloc (const size_t nx, const size_t ny)
{
const size_t n = nx * ny;
gsl_histogram2d_pdf *p;
if (n == 0)
{
GSL_ERROR_VAL ("histogram2d pdf length n must be positive integer",
GSL_EDOM, 0);
}
p = (gsl_histogram2d_pdf *) malloc (sizeof (gsl_histogram2d_pdf));
if (p == 0)
{
GSL_ERROR_VAL ("failed to allocate space for histogram2d pdf struct",
GSL_ENOMEM, 0);
}
p->xrange = (double *) malloc ((nx + 1) * sizeof (double));
if (p->xrange == 0)
{
free (p); /* exception in constructor, avoid memory leak */
GSL_ERROR_VAL ("failed to allocate space for histogram2d pdf xranges",
GSL_ENOMEM, 0);
}
p->yrange = (double *) malloc ((ny + 1) * sizeof (double));
if (p->yrange == 0)
{
free (p->xrange);
free (p); /* exception in constructor, avoid memory leak */
GSL_ERROR_VAL ("failed to allocate space for histogram2d pdf yranges",
GSL_ENOMEM, 0);
}
p->sum = (double *) malloc ((n + 1) * sizeof (double));
if (p->sum == 0)
{
free (p->yrange);
free (p->xrange);
free (p); /* exception in constructor, avoid memory leak */
GSL_ERROR_VAL ("failed to allocate space for histogram2d pdf sums",
GSL_ENOMEM, 0);
}
p->nx = nx;
p->ny = ny;
return p;
}
int
gsl_histogram2d_pdf_init (gsl_histogram2d_pdf * p, const gsl_histogram2d * h)
{
size_t i;
const size_t nx = p->nx;
const size_t ny = p->ny;
const size_t n = nx * ny;
if (nx != h->nx || ny != h->ny)
{
GSL_ERROR ("histogram2d size must match pdf size", GSL_EDOM);
}
for (i = 0; i < n; i++)
{
if (h->bin[i] < 0)
{
GSL_ERROR ("histogram bins must be non-negative to compute"
"a probability distribution", GSL_EDOM);
}
}
for (i = 0; i < nx + 1; i++)
{
p->xrange[i] = h->xrange[i];
}
for (i = 0; i < ny + 1; i++)
{
p->yrange[i] = h->yrange[i];
}
{
double mean = 0, sum = 0;
for (i = 0; i < n; i++)
{
mean += (h->bin[i] - mean) / ((double) (i + 1));
}
p->sum[0] = 0;
for (i = 0; i < n; i++)
{
sum += (h->bin[i] / mean) / n;
p->sum[i + 1] = sum;
}
}
return GSL_SUCCESS;
}
void
gsl_histogram2d_pdf_free (gsl_histogram2d_pdf * p)
{
free (p->xrange);
free (p->yrange);
free (p->sum);
free (p);
}
|
