GRASS GIS 8 Programmer's Manual 8.2.1RC1(2022)-exported
c_kurt.c
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1#include <grass/gis.h>
2#include <grass/raster.h>
3
4void c_kurt(DCELL * result, DCELL * values, int n, const void *closure)
5{
6 DCELL sum, ave, sumsq, sumqt, var;
7 int count;
8 int i;
9
10 sum = 0.0;
11 count = 0;
12
13 for (i = 0; i < n; i++) {
14 if (Rast_is_d_null_value(&values[i]))
15 continue;
16
17 sum += values[i];
18 count++;
19 }
20
21 if (count == 0) {
22 Rast_set_d_null_value(result, 1);
23 return;
24 }
25
26 ave = sum / count;
27
28 sumsq = 0;
29 sumqt = 0;
30
31 for (i = 0; i < n; i++) {
32 DCELL d;
33
34 if (Rast_is_d_null_value(&values[i]))
35 continue;
36
37 d = values[i] - ave;
38 sumsq += d * d;
39 sumqt += d * d * d * d;
40 }
41
42 var = sumsq / count;
43
44 *result = sumqt / (count * var * var) - 3;
45}
46
47void w_kurt(DCELL * result, DCELL(*values)[2], int n, const void *closure)
48{
49 DCELL sum, ave, sumsq, sumqt, var;
50 DCELL count;
51 int i;
52
53 sum = 0.0;
54 count = 0;
55
56 for (i = 0; i < n; i++) {
57 if (Rast_is_d_null_value(&values[i][0]))
58 continue;
59
60 sum += values[i][0] * values[i][1];
61 count += values[i][1];
62 }
63
64 if (count == 0) {
65 Rast_set_d_null_value(result, 1);
66 return;
67 }
68
69 ave = sum / count;
70
71 sumsq = 0;
72 sumqt = 0;
73
74 for (i = 0; i < n; i++) {
75 DCELL d;
76
77 if (Rast_is_d_null_value(&values[i][0]))
78 continue;
79
80 d = values[i][0] - ave;
81 sumsq += d * d * values[i][1];
82 sumqt += d * d * d * values[i][1];
83 }
84
85 var = sumsq / count;
86
87 *result = sumqt / (count * var * var) - 3;
88}
void c_kurt(DCELL *result, DCELL *values, int n, const void *closure)
Definition: c_kurt.c:4
void w_kurt(DCELL *result, DCELL(*values)[2], int n, const void *closure)
Definition: c_kurt.c:47
int count