GRASS GIS 8 Programmer's Manual 8.4.1(2025)-45ca3179ab
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xacos.c
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1#include <stdlib.h>
2#include <math.h>
3
4#include <grass/gis.h>
5#include <grass/raster.h>
6#include <grass/calc.h>
7
8/**********************************************************************
9acos(x) [0 and PI]
10
11 if floating point exception occurs during the evaluation of acos(x)
12 the result is NULL
13
14 note: result is in degrees
15**********************************************************************/
16
17#define RADIANS_TO_DEGREES (180.0 / M_PI)
18
19int f_acos(int argc, const int *argt, void **args)
20{
21 DCELL *res = args[0];
22 DCELL *arg1 = args[1];
23 int i;
24
25 if (argc < 1)
26 return E_ARG_LO;
27 if (argc > 1)
28 return E_ARG_HI;
29
30 if (argt[0] != DCELL_TYPE)
31 return E_RES_TYPE;
32
33 if (argt[1] != DCELL_TYPE)
34 return E_ARG_TYPE;
35
36 for (i = 0; i < columns; i++)
37 if (IS_NULL_D(&arg1[i]))
38 SET_NULL_D(&res[i]);
39 else {
41 res[i] = RADIANS_TO_DEGREES * acos(arg1[i]);
43 SET_NULL_D(&res[i]);
44 }
45
46 return 0;
47}
volatile int floating_point_exception
Definition calc.c:8
int columns
Definition calc.c:11
int f_acos(int argc, const int *argt, void **args)
Definition xacos.c:19
#define RADIANS_TO_DEGREES
Definition xacos.c:17