GRASS GIS 8 Programmer's Manual 8.4.1(2025)-45ca3179ab
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cmmult.c
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1/* cmmult.c CCMATH mathematics library source code.
2 *
3 * Copyright (C) 2000 Daniel A. Atkinson All rights reserved.
4 * This code may be redistributed under the terms of the GNU library
5 * public license (LGPL). ( See the lgpl.license file for details.)
6 * ------------------------------------------------------------------------
7 */
8
9#include <stdlib.h>
10#include "ccmath.h"
11
12void cmmult(Cpx *cm, Cpx *a, Cpx *b, int n, int m, int l)
13{
14 Cpx z, *q0, *p, *q;
15
16 int i, j, k;
17
18 q0 = (Cpx *)calloc(m, sizeof(Cpx));
19 for (i = 0; i < l; ++i, ++cm) {
20 for (k = 0, p = b + i; k < m; p += l)
21 q0[k++] = *p;
22 for (j = 0, p = a, q = cm; j < n; ++j, q += l) {
23 for (k = 0, z.re = z.im = 0.; k < m; ++k, ++p) {
24 z.re += p->re * q0[k].re - p->im * q0[k].im;
25 z.im += p->im * q0[k].re + p->re * q0[k].im;
26 }
27 *q = z;
28 }
29 }
30 free(q0);
31}
struct complex Cpx
Definition ccmath.h:41
void cmmult(Cpx *cm, Cpx *a, Cpx *b, int n, int m, int l)
Definition cmmult.c:12
double b
double l
double re
Definition ccmath.h:39
double im
Definition ccmath.h:39