/* * principal component analysis (PCA) * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at> * * This file is part of FFmpeg. * * FFmpeg 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 2.1 of the License, or (at your option) any later version. * * FFmpeg 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 FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include "libavutil/pca.c" #include "libavutil/lfg.h" #undef printf #include <stdio.h> #include <stdlib.h> int main(void){ PCA *pca; int i, j, k; #define LEN 8 double eigenvector[LEN*LEN]; double eigenvalue[LEN]; AVLFG prng; av_lfg_init(&prng, 1); pca= ff_pca_init(LEN); for(i=0; i<9000000; i++){ double v[2*LEN+100]; double sum=0; int pos = av_lfg_get(&prng) % LEN; int v2 = av_lfg_get(&prng) % 101 - 50; v[0] = av_lfg_get(&prng) % 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 += av_lfg_get(&prng) % 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"); } 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"); 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; }