FFmpeg
pca.c
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1 /*
2  * principal component analysis (PCA)
3  * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "libavutil/pca.c"
23 #include "libavutil/lfg.h"
24 
25 #undef printf
26 #include <stdio.h>
27 #include <stdlib.h>
28 
29 int main(void){
30  PCA *pca;
31  int i, j, k;
32 #define LEN 8
33  double eigenvector[LEN*LEN];
34  double eigenvalue[LEN];
35  AVLFG prng;
36 
37  av_lfg_init(&prng, 1);
38 
39  pca= ff_pca_init(LEN);
40 
41  for(i=0; i<9000000; i++){
42  double v[2*LEN+100];
43  double sum=0;
44  int pos = av_lfg_get(&prng) % LEN;
45  int v2 = av_lfg_get(&prng) % 101 - 50;
46  v[0] = av_lfg_get(&prng) % 101 - 50;
47  for(j=1; j<8; j++){
48  if(j<=pos) v[j]= v[0];
49  else v[j]= v2;
50  sum += v[j];
51  }
52 /* for(j=0; j<LEN; j++){
53  v[j] -= v[pos];
54  }*/
55 // sum += av_lfg_get(&prng) % 10;
56 /* for(j=0; j<LEN; j++){
57  v[j] -= sum/LEN;
58  }*/
59 // lbt1(v+100,v+100,LEN);
60  ff_pca_add(pca, v);
61  }
62 
63 
64  ff_pca(pca, eigenvector, eigenvalue);
65  for(i=0; i<LEN; i++){
66  pca->count= 1;
67  pca->mean[i]= 0;
68 
69 // (0.5^|x|)^2 = 0.5^2|x| = 0.25^|x|
70 
71 
72 // pca.covariance[i + i*LEN]= pow(0.5, fabs
73  for(j=i; j<LEN; j++){
74  printf("%f ", pca->covariance[i + j*LEN]);
75  }
76  printf("\n");
77  }
78 
79  for(i=0; i<LEN; i++){
80  double v[LEN];
81  double error=0;
82  memset(v, 0, sizeof(v));
83  for(j=0; j<LEN; j++){
84  for(k=0; k<LEN; k++){
85  v[j] += pca->covariance[FFMIN(k,j) + FFMAX(k,j)*LEN] * eigenvector[i + k*LEN];
86  }
87  v[j] /= eigenvalue[i];
88  error += fabs(v[j] - eigenvector[i + j*LEN]);
89  }
90  printf("%f ", error);
91  }
92  printf("\n");
93 
94  for(i=0; i<LEN; i++){
95  for(j=0; j<LEN; j++){
96  printf("%9.6f ", eigenvector[i + j*LEN]);
97  }
98  printf(" %9.1f %f\n", eigenvalue[i], eigenvalue[i]/eigenvalue[0]);
99  }
100 
101  return 0;
102 }
Context structure for the Lagged Fibonacci PRNG.
Definition: lfg.h:33
Definition: pca.c:30
int count
Definition: pca.c:31
#define LEN
static void error(const char *err)
PCA * ff_pca_init(int n)
Definition: pca.c:38
unsigned int pos
Definition: spdifenc.c:410
#define FFMAX(a, b)
Definition: common.h:94
#define FFMIN(a, b)
Definition: common.h:96
int main(void)
Definition: pca.c:29
int ff_pca(PCA *pca, double *eigenvector, double *eigenvalue)
Definition: pca.c:80
static unsigned int av_lfg_get(AVLFG *c)
Get the next random unsigned 32-bit number using an ALFG.
Definition: lfg.h:53
principal component analysis (PCA)
void ff_pca_add(PCA *pca, const double *v)
Definition: pca.c:68
av_cold void av_lfg_init(AVLFG *c, unsigned int seed)
Definition: lfg.c:32
double * mean
Definition: pca.c:34
printf("static const uint8_t my_array[100] = {\n")
double * covariance
Definition: pca.c:33
int i
Definition: input.c:407