GRASS GIS 8 Programmer's Manual 8.3.2(2024)-exported
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durbins.c
Go to the documentation of this file.
1#include <stdio.h>
2#include <stdlib.h>
3#include <math.h>
4#include "local_proto.h"
5
6/* could probably use some cleanup/optimization */
7double *Cdhc_durbins_exact(double *x, int n)
8{
9 static double y[2];
10 double *xcopy, sumx = 0.0, sumx2 = 0.0, s2, *b, *c, *g, *z, sqrt2;
11 int i, j;
12
13 if ((b = (double *)malloc(n * sizeof(double))) == NULL) {
14 fprintf(stderr, "Memory error in Cdhc_durbins_exact\n");
15 exit(EXIT_FAILURE);
16 }
17 if ((c = (double *)malloc((n + 1) * sizeof(double))) == NULL) {
18 fprintf(stderr, "Memory error in Cdhc_durbins_exact\n");
19 exit(EXIT_FAILURE);
20 }
21 if ((g = (double *)malloc((n + 1) * sizeof(double))) == NULL) {
22 fprintf(stderr, "Memory error in Cdhc_durbins_exact\n");
23 exit(EXIT_FAILURE);
24 }
25 if ((z = (double *)malloc(n * sizeof(double))) == NULL) {
26 fprintf(stderr, "Memory error in Cdhc_durbins_exact\n");
27 exit(EXIT_FAILURE);
28 }
29 if ((xcopy = (double *)malloc(n * sizeof(double))) == NULL) {
30 fprintf(stderr, "Memory error in Cdhc_durbins_exact\n");
31 exit(EXIT_FAILURE);
32 }
33
34 sqrt2 = sqrt((double)2.0);
35 for (i = 0; i < n; ++i) {
36 xcopy[i] = x[i];
37 sumx += x[i];
38 sumx2 += x[i] * x[i];
39 }
40
41 s2 = sqrt((sumx2 - sumx * sumx / n) / (n - 1));
42 for (i = 0; i < n; ++i) {
43 xcopy[i] = (xcopy[i] - sumx / n) / s2;
44 b[i] = 0.5 + Cdhc_normp(xcopy[i] / sqrt2) / 2.0;
45 }
46
47 qsort(b, n, sizeof(double), Cdhc_dcmp);
48
49 for (i = 1; i < n; ++i)
50 c[i] = b[i] - b[i - 1];
51
52 c[0] = b[0];
53 c[n] = 1 - b[n - 1];
54
55 qsort(c, n + 1, sizeof(double), Cdhc_dcmp);
56
57 for (j = 1; j <= n; ++j)
58 g[j] = (n + 1 - j) * (c[j] - c[j - 1]);
59
60 g[0] = (n + 1) * c[0];
61 g[n] = c[n] - c[n - 1];
62
63 for (i = 0; i < n; ++i) {
64 z[i] = 0.0;
65 for (j = 0; j <= i; ++j)
66 z[i] += g[j];
67
68 z[i] = (i + 1.0) / n - z[i];
69 }
70
71 qsort(z, n, sizeof(double), Cdhc_dcmp);
72
73 y[0] = z[n - 1];
74 y[1] = sqrt((double)n) * z[n - 1];
75
76#ifdef NOISY
77 fprintf(stdout, " TEST7 DRB(N) =%10.4f\n", y[0]);
78#endif /* NOISY */
79
80 free(b);
81 free(c);
82 free(g);
83 free(xcopy);
84 free(z);
85
86 return y;
87}
#define NULL
Definition ccmath.h:32
int Cdhc_dcmp(const void *i, const void *j)
Definition dcmp.c:1
double b
double * Cdhc_durbins_exact(double *x, int n)
Definition durbins.c:7
float g
Definition named_colr.c:7
double Cdhc_normp(double z)
Definition normp.c:22
#define x