[FFmpeg-cvslog] r14802 - in trunk/libavutil: pca.c pca.h
michael
subversion
Sun Aug 17 17:28:12 CEST 2008
Author: michael
Date: Sun Aug 17 17:28:12 2008
New Revision: 14802
Log:
Principal component analysis
(will be cleaned up in next commits)
Added:
trunk/libavutil/pca.c
trunk/libavutil/pca.h
Added: trunk/libavutil/pca.c
==============================================================================
--- (empty file)
+++ trunk/libavutil/pca.c Sun Aug 17 17:28:12 2008
@@ -0,0 +1,231 @@
+/*
+ * Principal component analysis
+ * Copyright (c) 2004 Michael Niedermayer <michaelni at gmx.at>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+
+/**
+ * @file pca.c
+ * Principal component analysis
+ */
+
+#include <math.h>
+#include "avcodec.h"
+#include "pca.h"
+
+int ff_pca_init(PCA *pca, int n){
+ if(n<=0)
+ return -1;
+
+ pca->n= n;
+ pca->count=0;
+ pca->covariance= av_mallocz(sizeof(double)*n*n);
+ pca->mean= av_mallocz(sizeof(double)*n);
+
+ return 0;
+}
+
+void ff_pca_free(PCA *pca){
+ av_freep(&pca->covariance);
+ av_freep(&pca->mean);
+}
+
+void ff_pca_add(PCA *pca, double *v){
+ int i, j;
+ const int n= pca->n;
+
+ for(i=0; i<n; i++){
+ pca->mean[i] += v[i];
+ for(j=i; j<n; j++)
+ pca->covariance[j + i*n] += v[i]*v[j];
+ }
+ pca->count++;
+}
+
+int ff_pca(PCA *pca, double *eigenvector, double *eigenvalue){
+ int i, j, k, pass;
+ const int n= pca->n;
+ double z[n];
+
+ memset(eigenvector, 0, sizeof(double)*n*n);
+
+ for(j=0; j<n; j++){
+ pca->mean[j] /= pca->count;
+ eigenvector[j + j*n] = 1.0;
+ for(i=0; i<=j; i++){
+ pca->covariance[j + i*n] /= pca->count;
+ pca->covariance[j + i*n] -= pca->mean[i] * pca->mean[j];
+ pca->covariance[i + j*n] = pca->covariance[j + i*n];
+ }
+ eigenvalue[j]= pca->covariance[j + j*n];
+ z[j]= 0;
+ }
+
+ for(pass=0; pass < 50; pass++){
+ double sum=0;
+
+ for(i=0; i<n; i++)
+ for(j=i+1; j<n; j++)
+ sum += fabs(pca->covariance[j + i*n]);
+
+ if(sum == 0){
+ for(i=0; i<n; i++){
+ double maxvalue= -1;
+ for(j=i; j<n; j++){
+ if(eigenvalue[j] > maxvalue){
+ maxvalue= eigenvalue[j];
+ k= j;
+ }
+ }
+ eigenvalue[k]= eigenvalue[i];
+ eigenvalue[i]= maxvalue;
+ for(j=0; j<n; j++){
+ double tmp= eigenvector[k + j*n];
+ eigenvector[k + j*n]= eigenvector[i + j*n];
+ eigenvector[i + j*n]= tmp;
+ }
+ }
+ return pass;
+ }
+
+ for(i=0; i<n; i++){
+ for(j=i+1; j<n; j++){
+ double covar= pca->covariance[j + i*n];
+ double t,c,s,tau,theta, h;
+
+ if(pass < 3 && fabs(covar) < sum / (5*n*n)) //FIXME why pass < 3
+ continue;
+ if(fabs(covar) == 0.0) //FIXME shouldnt be needed
+ continue;
+ if(pass >=3 && fabs((eigenvalue[j]+z[j])/covar) > (1LL<<32) && fabs((eigenvalue[i]+z[i])/covar) > (1LL<<32)){
+ pca->covariance[j + i*n]=0.0;
+ continue;
+ }
+
+ h= (eigenvalue[j]+z[j]) - (eigenvalue[i]+z[i]);
+ theta=0.5*h/covar;
+ t=1.0/(fabs(theta)+sqrt(1.0+theta*theta));
+ if(theta < 0.0) t = -t;
+
+ c=1.0/sqrt(1+t*t);
+ s=t*c;
+ tau=s/(1.0+c);
+ z[i] -= t*covar;
+ z[j] += t*covar;
+
+#define ROTATE(a,i,j,k,l)\
+ double g=a[j + i*n];\
+ double h=a[l + k*n];\
+ a[j + i*n]=g-s*(h+g*tau);\
+ a[l + k*n]=h+s*(g-h*tau);
+ for(k=0; k<n; k++) {
+ if(k!=i && k!=j){
+ ROTATE(pca->covariance,FFMIN(k,i),FFMAX(k,i),FFMIN(k,j),FFMAX(k,j))
+ }
+ ROTATE(eigenvector,k,i,k,j)
+ }
+ pca->covariance[j + i*n]=0.0;
+ }
+ }
+ for (i=0; i<n; i++) {
+ eigenvalue[i] += z[i];
+ z[i]=0.0;
+ }
+ }
+
+ return -1;
+}
+
+#if 1
+
+#undef printf
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(){
+ PCA pca;
+ int i, j, k;
+#define LEN 8
+ double eigenvector[LEN*LEN];
+ double eigenvalue[LEN];
+
+ ff_pca_init(&pca, LEN);
+
+ for(i=0; i<9000000; i++){
+ double v[2*LEN+100];
+ double sum=0;
+ int pos= random()%LEN;
+ int v2= (random()%101) - 50;
+ v[0]= (random()%101) - 50;
+ for(j=1; j<8; j++){
+ if(j<=pos) v[j]= v[0];
+ else v[j]= v2;
+ sum += v[j];
+ }
+/* for(j=0; j<LEN; j++){
+ v[j] -= v[pos];
+ }*/
+// sum += random()%10;
+/* for(j=0; j<LEN; j++){
+ v[j] -= sum/LEN;
+ }*/
+// lbt1(v+100,v+100,LEN);
+ ff_pca_add(&pca, v);
+ }
+
+
+ ff_pca(&pca, eigenvector, eigenvalue);
+ for(i=0; i<LEN; i++){
+ pca.count= 1;
+ pca.mean[i]= 0;
+
+// (0.5^|x|)^2 = 0.5^2|x| = 0.25^|x|
+
+
+// pca.covariance[i + i*LEN]= pow(0.5, fabs
+ for(j=i; j<LEN; j++){
+ printf("%f ", pca.covariance[i + j*LEN]);
+ }
+ printf("\n");
+ }
+
+#if 1
+ for(i=0; i<LEN; i++){
+ double v[LEN];
+ double error=0;
+ memset(v, 0, sizeof(v));
+ for(j=0; j<LEN; j++){
+ for(k=0; k<LEN; k++){
+ v[j] += pca.covariance[FFMIN(k,j) + FFMAX(k,j)*LEN] * eigenvector[i + k*LEN];
+ }
+ v[j] /= eigenvalue[i];
+ error += fabs(v[j] - eigenvector[i + j*LEN]);
+ }
+ printf("%f ", error);
+ }
+ printf("\n");
+#endif
+ for(i=0; i<LEN; i++){
+ for(j=0; j<LEN; j++){
+ printf("%9.6f ", eigenvector[i + j*LEN]);
+ }
+ printf(" %9.1f %f\n", eigenvalue[i], eigenvalue[i]/eigenvalue[0]);
+ }
+
+ return 0;
+}
+#endif
Added: trunk/libavutil/pca.h
==============================================================================
--- (empty file)
+++ trunk/libavutil/pca.h Sun Aug 17 17:28:12 2008
@@ -0,0 +1,31 @@
+/*
+ * Principal component analysis
+ * Copyright (c) 2004 Michael Niedermayer <michaelni at gmx.at>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+
+/**
+ * @file pca.h
+ * Principal component analysis
+ */
+
+typedef struct PCA{
+ int count;
+ int n;
+ double *covariance;
+ double *mean;
+}PCA;
More information about the ffmpeg-cvslog
mailing list