GRASS GIS 8 Programmer's Manual 8.3.2(2024)-exported
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royston.c
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1#include <stdio.h>
2#include <stdlib.h>
3#include <math.h>
4#include "local_proto.h"
5
6/*-
7 * driver program for AS 181: Royston's extension of the Shapiro-Wilk
8 * W statistic to n=2000
9 * needs as181.c as177.c as241.c Cdhc_dcmp.c as66.c
10 */
11
12double *Cdhc_royston(double *x, int n)
13{
14 static double y[2];
15 double *a, eps, w, pw, mean = 0, ssq = 0, *xcopy;
16 int i, ifault, n2;
17
18 n2 = (int)floor((double)n / 2);
19
20#ifndef lint
21 if ((a = (double *)malloc(n2 * sizeof(double))) == NULL) {
22 fprintf(stderr, "Memory error in royston\n");
23 exit(EXIT_FAILURE);
24 }
25 if ((xcopy = (double *)malloc(n * sizeof(double))) == NULL) {
26 fprintf(stderr, "Memory error in royston\n");
27 exit(EXIT_FAILURE);
28 }
29#endif /* lint */
30
31 for (i = 0; i < n; ++i) {
32 xcopy[i] = x[i];
33 mean += x[i];
34 }
35 mean /= n;
36
37 qsort(xcopy, n, sizeof(double), Cdhc_dcmp);
38
39 for (i = 0; i < n; ++i)
40 ssq += (mean - x[i]) * (mean - x[i]);
41
42 wcoef(a, n, n2, &eps, &ifault);
43
44 if (ifault == 0)
45 wext(xcopy, n, ssq, a, n2, eps, &w, &pw, &ifault);
46 else {
47 fprintf(stderr, "Error in wcoef()\n");
48 return (double *)NULL;
49 }
50
51 if (ifault == 0) {
52 y[0] = w;
53 y[1] = pw;
54 }
55 else {
56 fprintf(stderr, "Error in wcoef()\n");
57 return (double *)NULL;
58 }
59
60 free(a);
61 free(xcopy);
62
63 return y;
64}
void wext(double x[], int n, double ssq, double a[], int n2, double eps, double *w, double *pw, int *ifault)
Definition as181.c:23
void wcoef(double a[], int n, int n2, double *eps, int *ifault)
Definition as181.c:166
#define NULL
Definition ccmath.h:32
int Cdhc_dcmp(const void *i, const void *j)
Definition dcmp.c:1
double * Cdhc_royston(double *x, int n)
Definition royston.c:12
#define x