|
rlm@8
|
1 #include <stdio.h>
|
|
rlm@8
|
2 #include <stdlib.h>
|
|
rlm@8
|
3 #include <math.h>
|
|
rlm@8
|
4
|
|
rlm@8
|
5
|
|
rlm@8
|
6 int DFT(int dir,int m,double *x1,double *y1)
|
|
rlm@8
|
7 {
|
|
rlm@8
|
8 long i,k;
|
|
rlm@8
|
9 double arg;
|
|
rlm@8
|
10 double cosarg,sinarg;
|
|
rlm@8
|
11 double *x2=NULL,*y2=NULL;
|
|
rlm@8
|
12
|
|
rlm@8
|
13 x2 = (double *)(malloc(m*sizeof(double)));
|
|
rlm@8
|
14 y2 = (double *)(malloc(m*sizeof(double)));
|
|
rlm@8
|
15 if (x2 == NULL || y2 == NULL)
|
|
rlm@8
|
16 return 0;
|
|
rlm@8
|
17
|
|
rlm@8
|
18 for (i=0;i<m;i++) {
|
|
rlm@8
|
19 x2[i] = 0;
|
|
rlm@8
|
20 y2[i] = 0;
|
|
rlm@8
|
21 arg = - dir * 2.0 * 3.141592654 * (double)i / (double)m;
|
|
rlm@8
|
22 for (k=0;k<m;k++) {
|
|
rlm@8
|
23 cosarg = cos(k * arg);
|
|
rlm@8
|
24 sinarg = sin(k * arg);
|
|
rlm@8
|
25 x2[i] += (x1[k] * cosarg - y1[k] * sinarg);
|
|
rlm@8
|
26 y2[i] += (x1[k] * sinarg + y1[k] * cosarg);
|
|
rlm@8
|
27 }
|
|
rlm@8
|
28 }
|
|
rlm@8
|
29
|
|
rlm@8
|
30 /* Copy the data back */
|
|
rlm@8
|
31 if (dir == 1) {
|
|
rlm@8
|
32 for (i=0;i<m;i++) {
|
|
rlm@8
|
33 x1[i] = x2[i];
|
|
rlm@8
|
34 y1[i] = y2[i];
|
|
rlm@8
|
35 }
|
|
rlm@8
|
36 } else {
|
|
rlm@8
|
37 for (i=0;i<m;i++) {
|
|
rlm@8
|
38 x1[i] = x2[i];
|
|
rlm@8
|
39 y1[i] = y2[i];
|
|
rlm@8
|
40 }
|
|
rlm@8
|
41 }
|
|
rlm@8
|
42
|
|
rlm@8
|
43 free(x2);
|
|
rlm@8
|
44 free(y2);
|
|
rlm@8
|
45 return 1;
|
|
rlm@8
|
46 }
|
