libs/qm-dsp/maths/CosineDistance.cpp

   1 /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
   2
   3 /*
   4     QM DSP Library
   5
   6     Centre for Digital Music, Queen Mary, University of London.
   7     This file copyright 2008 Kurt Jacobson.
   8
   9     This program is free software; you can redistribute it and/or
  10     modify it under the terms of the GNU General Public License as
  11     published by the Free Software Foundation; either version 2 of the
  12     License, or (at your option) any later version.  See the file
  13     COPYING included with this distribution for more information.
  14 */
  15
  16 #include "CosineDistance.h"
  17
  18 #include <iostream>
  19 #include <limits>
  20
  21 using std::cerr;
  22
  23 double CosineDistance::distance(const vector<double> &v1,
  24                                 const vector<double> &v2)
  25 {
  26     dist = 1.0; dDenTot = 0; dDen1 = 0; dDen2 = 0; dSum1 =0;
  27     double small = 1e-20;
  28
  29     //check if v1, v2 same size
  30     if (v1.size() != v2.size())
  31     {
  32         cerr << "CosineDistance::distance: ERROR: vectors not the same size\n";
  33         return 1.0;
  34     }
  35     else
  36     {
  37         for(int i=0; i<v1.size(); i++)
  38         {
  39             dSum1 += v1[i]*v2[i];
  40             dDen1 += v1[i]*v1[i];
  41             dDen2 += v2[i]*v2[i];
  42         }
  43         dDenTot = sqrt(fabs(dDen1*dDen2)) + small;
  44         dist = 1-((dSum1)/dDenTot);
  45         return dist;
  46     }
  47 }