/usr/include/dune/localfunctions/utility/lfematrix.hh is in libdune-localfunctions-dev 2.5.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_LOCALFUNCTIONS_UTILITY_LFEMATRIX_HH
#define DUNE_LOCALFUNCTIONS_UTILITY_LFEMATRIX_HH
#include <cassert>
#include <vector>
#include "field.hh"
namespace Dune
{
template< class F >
class LFEMatrix
{
typedef LFEMatrix< F > This;
typedef std::vector< F > Row;
typedef std::vector<Row> RealMatrix;
public:
typedef F Field;
operator const RealMatrix & () const
{
return matrix_;
}
operator RealMatrix & ()
{
return matrix_;
}
template <class Vector>
void row( const unsigned int row, Vector &vec ) const
{
assert(row<rows());
for (int i=0; i<cols(); ++i)
field_cast(matrix_[row][i], vec[i]);
}
const Field &operator() ( const unsigned int row, const unsigned int col ) const
{
assert(row<rows());
assert(col<cols());
return matrix_[ row ][ col ];
}
Field &operator() ( const unsigned int row, const unsigned int col )
{
assert(row<rows());
assert(col<cols());
return matrix_[ row ][ col ];
}
unsigned int rows () const
{
return rows_;
}
unsigned int cols () const
{
return cols_;
}
const Field *rowPtr ( const unsigned int row ) const
{
assert(row<rows());
return &(matrix_[row][0]);
}
Field *rowPtr ( const unsigned int row )
{
assert(row<rows());
return &(matrix_[row][0]);
}
void resize ( const unsigned int rows, const unsigned int cols )
{
matrix_.resize(rows);
for (unsigned int i=0; i<rows; ++i)
matrix_[i].resize(cols);
rows_ = rows;
cols_ = cols;
}
bool invert ()
{
assert( rows() == cols() );
std::vector<unsigned int> p(rows());
for (unsigned int j=0; j<rows(); ++j)
p[j] = j;
for (unsigned int j=0; j<rows(); ++j)
{
// pivot search
unsigned int r = j;
Field max = std::abs( (*this)(j,j) );
for (unsigned int i=j+1; i<rows(); ++i)
{
if ( std::abs( (*this)(i,j) ) > max )
{
max = std::abs( (*this)(i,j) );
r = i;
}
}
if (max == Zero<Field>())
return false;
// row swap
if (r > j)
{
for (unsigned int k=0; k<cols(); ++k)
std::swap( (*this)(j,k), (*this)(r,k) );
std::swap( p[j], p[r] );
}
// transformation
Field hr = Unity<Field>()/(*this)(j,j);
for (unsigned int i=0; i<rows(); ++i)
(*this)(i,j) *= hr;
(*this)(j,j) = hr;
for (unsigned int k=0; k<cols(); ++k)
{
if (k==j) continue;
for (unsigned int i=0; i<rows(); ++i)
{
if (i==j) continue;
(*this)(i,k) -= (*this)(i,j)*(*this)(j,k);
}
(*this)(j,k) *= -hr;
}
}
// column exchange
Row hv(rows());
for (unsigned int i=0; i<rows(); ++i)
{
for (unsigned int k=0; k<rows(); ++k)
hv[ p[k] ] = (*this)(i,k);
for (unsigned int k=0; k<rows(); ++k)
(*this)(i,k) = hv[k];
}
return true;
}
private:
RealMatrix matrix_;
unsigned int cols_,rows_;
};
template< class Field >
inline std::ostream &operator<<(std::ostream &out, const LFEMatrix<Field> &mat)
{
for (unsigned int r=0; r<mat.rows(); ++r)
{
out << field_cast<double>(mat(r,0));
for (unsigned int c=1; c<mat.cols(); ++c)
{
out << " , " << field_cast<double>(mat(r,c));
}
out << std::endl;
}
return out;
}
}
#endif // #ifndef DUNE_LOCALFUNCTIONS_UTILITY_LFEMATRIX_HH
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