GRASS GIS 8 Programmer's Manual 8.3.2(2024)-exported
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watsonun.c
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1#include <stdio.h>
2#include <stdlib.h>
3#include <math.h>
4#include "local_proto.h"
5
6double *Cdhc_watson_u2(double *x, int n)
7{
8 double *xcopy, mean = 0.0, sdx = 0.0, sqrt2, zbar = 0.0;
9 double fn2, fx, sum4 = 0.0;
10 static double y[2];
11 int i;
12
13 sqrt2 = sqrt((double)2.0);
14
15 if ((xcopy = (double *)malloc(n * sizeof(double))) == NULL) {
16 fprintf(stderr, "Memory error in Cdhc_anderson_darling\n");
17 exit(EXIT_FAILURE);
18 }
19
20 for (i = 0; i < n; ++i) {
21 xcopy[i] = x[i];
22 mean += x[i];
23 sdx += x[i] * x[i];
24 }
25 sdx = sqrt((n * sdx - mean * mean) / (n * (n - 1)));
26 mean /= n;
27
28 qsort(xcopy, n, sizeof(double), Cdhc_dcmp);
29
30 for (i = 0; i < n; ++i) {
31 xcopy[i] = (xcopy[i] - mean) / sdx;
32 fn2 = (2.0 * (i + 1) - 1.0) / (2.0 * n);
33 fx = 0.5 + Cdhc_normp(xcopy[i] / sqrt2) / 2.0;
34
35 if (fx <= 0.0)
36 fx = 1e-5;
37
38 if (fx >= 1.0)
39 fx = 0.99999;
40
41 zbar += fx;
42 sum4 += (fx - fn2) * (fx - fn2);
43 }
44
45 zbar /= n;
46 y[0] = (1.0 / (n * 12) + sum4) - n * (zbar - .5) * (zbar - .5);
47 y[0] *= 0.5 / n + 1.0;
48
49#ifdef NOISY
50 fprintf(stdout, " TEST6 WU2(N) =%10.4f\n", y[0]);
51#endif /* NOISY */
52
53 free(xcopy);
54
55 return y;
56}
#define NULL
Definition ccmath.h:32
int Cdhc_dcmp(const void *i, const void *j)
Definition dcmp.c:1
double Cdhc_normp(double z)
Definition normp.c:22
double * Cdhc_watson_u2(double *x, int n)
Definition watsonun.c:6
#define x