GRASS GIS 8 Programmer's Manual 8.2.1RC1(2022)-exported
dmax.c
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1#include <stdio.h>
2#include <stdlib.h>
3#include <math.h>
4#include "local_proto.h"
5
6
7double *Cdhc_dmax(double *x, int n)
8{
9 static double y[2];
10 double *xcopy, sqrt2, sqrtn, mean = 0.0, sdx = 0.0, fx;
11 double dp, dp_max, dm, dm_max;
12 int i;
13
14 if ((xcopy = (double *)malloc(n * sizeof(double))) == NULL) {
15 fprintf(stderr, "Memory error in Cdhc_dmax\n");
16 exit(EXIT_FAILURE);
17 }
18
19 sqrt2 = sqrt((double)2.0);
20 sqrtn = sqrt((double)n);
21
22 for (i = 0; i < n; ++i) {
23 xcopy[i] = x[i];
24 mean += x[i];
25 sdx += x[i] * x[i];
26 }
27 sdx = sqrt((n * sdx - mean * mean) / (n * (n - 1.0)));
28 mean /= n;
29
30 qsort(xcopy, n, sizeof(double), Cdhc_dcmp);
31
32 for (i = 0; i < n; ++i) {
33 xcopy[i] = (xcopy[i] - mean) / sdx;
34 fx = 0.5 + Cdhc_normp(xcopy[i] / sqrt2) / 2.0;
35 if (fx <= 1e-5)
36 fx = 1e-5;
37
38 if (fx >= 0.99999)
39 fx = 0.99999;
40
41 dp = (double)(i + 1) / (double)n - fx;
42 dm = fx - i / (double)n;
43 if (i == 0 || dp > dp_max)
44 dp_max = dp;
45
46 if (i == 0 || dm > dm_max)
47 dm_max = dm;
48 }
49
50 y[0] = dp_max;
51 y[1] = dm_max;
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_dmax(double *x, int n)
Definition: dmax.c:7
double Cdhc_normp(double z)
Definition: normp.c:23
#define x