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/*!
* \file
* \brief Implementation of special operations on vectors and matricies
* optimized for speed
* \author Tony Ottosson and Tobias Ringstrom
*
* -------------------------------------------------------------------------
*
* Copyright (C) 1995-2010 (see AUTHORS file for a list of contributors)
*
* This file is part of IT++ - a C++ library of mathematical, signal
* processing, speech processing, and communications classes and functions.
*
* IT++ 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 3 of the License, or (at your option) any
* later version.
*
* IT++ 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 IT++. If not, see <http://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
*/
#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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