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/*!
* \file
* \brief Implementation of special operations on vectors and matricies
* optimized for speed
* \author Tony Ottosson and Tobias Ringstrom
*
* -------------------------------------------------------------------------
*
* IT++ - C++ library of mathematical, signal processing, speech processing,
* and communications classes and functions
*
* Copyright (C) 1995-2008 (see AUTHORS file for a list of contributors)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* -------------------------------------------------------------------------
*/
#include <itpp/base/fastmath.h>
namespace itpp {
// m=m-v*v'*m
void sub_v_vT_m(mat &m, const vec &v)
{
vec v2(m.cols());
double tmp, *v2p;
const double *vp;
int i, j;
it_assert(v.size() == m.rows(), "sub_v_vT_m()");
v2p = v2._data();
for (j=0; j<m.cols(); j++) {
tmp = 0.0;
vp=v._data();
for (i=0; i<m.rows(); i++)
tmp += *(vp++) * m._elem(i,j);
*(v2p++) = tmp;
}
vp=v._data();
for (i=0; i<m.rows(); i++) {
v2p = v2._data();
for (j=0; j<m.cols(); j++)
m._elem(i,j) -= *vp * *(v2p++);
vp++;
}
}
// m=m-m*v*v'
void sub_m_v_vT(mat &m, const vec &v)
{
vec v2(m.rows());
double tmp, *v2p;
const double *vp;
int i, j;
it_assert(v.size() == m.cols(), "sub_m_v_vT()");
v2p = v2._data();
for (i=0; i<m.rows(); i++) {
tmp = 0.0;
vp = v._data();
for (j=0; j<m.cols(); j++)
tmp += *(vp++) * m._elem(i,j);
*(v2p++) = tmp;
}
v2p = v2._data();
for (i=0; i<m.rows(); i++) {
vp=v._data();
for (j=0; j<m.cols(); j++)
m._elem(i,j) -= *v2p * *(vp++);
v2p++;
}
}
} // namespace itpp
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