LaVtMVSimilarity.cxx

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// @(#)root/minuit2:$Id$
// Authors: M. Winkler, F. James, L. Moneta, A. Zsenei   2003-2005
 
/**********************************************************************
 *                                                                    *
 * Copyright (c) 2005 LCG ROOT Math team,  CERN/PH-SFT                *
 *                                                                    *
 **********************************************************************/
 
#include "Minuit2/LASymMatrix.h"
#include "Minuit2/LAVector.h"
#include "Minuit2/LaProd.h"
 
namespace ROOT {
 
namespace Minuit2 {
 
double mnddot(unsigned int, const double *, int, const double *, int);
 
double similarity(const LAVector &avec, const LASymMatrix &mat)
{
   // calculate the similarity vector-matrix product: V^T M V
   // use matrix product and then dot function (using mnddot)
 
   LAVector tmp = mat * avec;
 
   double value = mnddot(avec.size(), avec.Data(), 1, tmp.Data(), 1);
   return value;
}
 
} // namespace Minuit2
 
} // namespace ROOT