bool same_order(const SMatrix& m1, const SMatrix& m2)
{
if(m1.getRows() == m2.getRows() && m1.getCols() == m2.getCols())
return true;
else
return false;
}
/**
* Divide the matrix by the given matrix. The matrixes must be the same size
* this is checked via assertions. We perform the division by multiplication
* of the inverse so this is a costly operation.
*
* @param im The matrix to divide by
*/
SMatrix SMatrix::operator /( const SMatrix &im ) const
{
assert( this->getCols() == im.getCols() && "Amount of Columns Differ");
assert( this->getRows() == im.getRows() && "Amount of Rows Differ" );
return (*this) * inv ( im );
}
bool SMatrix::equal(const SMatrix& otherMat) const
{
if(cols == otherMat.getCols() && rows == otherMat.getRows())
return true;
else
return false;
}
bool multiplicable(const SMatrix& m1, const SMatrix& m2)
{
if( m1.getRows() == m2.getCols())
return true;
else
return false;
}
void output(std::ostream& outs, const SMatrix& src)
{ // NOTE: r and c are row # and coloum #, NOT indices
for(int r = 1; r <= src.getRows(); ++r)
{
for(int c = 1; c <= src.getCols(); ++c)
outs << setw(SMatrix::FIELD_WIDTH) << src.valAt(r, c);
outs << endl;
}
}
SMatrix add(const SMatrix& m1, const SMatrix& m2)
{
SMatrix newMat;
newMat.setRows(m1.getRows());
newMat.setCols(m1.getCols());
int result;
for( int i = 0; i < m1.getRows(); i++ )
{
for( int j = 0; j < m1.getCols(); j++ )
{
result = m1.valAt(i+1, j+1) + m2.valAt(i+1, j+1);
newMat.setVal(i, j, result);
}
}
return newMat;
}
SMatrix SMatrix::times(const SMatrix& otherMat) const
{
SMatrix newMat;
newMat.setRows(rows);
newMat.setCols(otherMat.getCols());
int result;
for( int i = 0; i < rows; i++ )
{
for( int k = 0; k < otherMat.getCols(); k++ )
{
result = 0;
for(int j = 0; j < otherMat.getRows(); j++ )
{
result+=(data[i][j] * otherMat.valAt(j+1, k+1));
}
newMat.setVal(i, k, result);
}
}
return newMat;
}
/**
* Calculate the determinate of matrix. Theres a number of
* ways to do this. Using coofactors of a matrix uses recursion so
* we avoid this. Instead we use Gauss-Jordan Elimination and use
* an iterative approach.
*
* This elimination comes into play due to the fact
* that if the elements in lower triangle of the
* matrix are all zeroes, the determinant is simply
* the product of the diagonals. This also applies
* in the upper triangle zeroes. It means the determinate
* ends up being the product of the main diagonal after elmination
*
*
* @param im The matrix to calculate the determinate of
*/
T det ( const SMatrix &im )
{
unsigned i, j, k;
T temp, factor, detvalue = 1.0;
// Determinate of a 1x1 matrix
if ( im.getRows() == 1 ){
return im[0][0];
}
// Determinate of a 2x2 matrix
else if ( im.getRows() == 2 ){
return im[0][0]*im[1][1] - im[1][0]*im[0][1];
}
// Determinate of a 3x3 matrix
else if ( im.getRows() == 3 ){
detvalue = -im[0][2]*im[1][1]*im[2][0];//-a02 a11 a20
detvalue += im[0][1]*im[1][2]*im[2][0];//+ a01 a12 a20
detvalue += im[0][2]*im[1][0]*im[2][1];//+ a02 a10 a21
detvalue -= im[0][0]*im[1][2]*im[2][1];//- a00 a12 a21
detvalue -= im[0][1]*im[1][0]*im[2][2];//- a01 a10 a22
detvalue += im[0][0]*im[1][1]*im[2][2];//+ a00 a11 a22
return detvalue;
}
// The determinate for any other size matrix
SMatrix m ( im );
for ( i = 0; i < m.getRows(); i++ ){
// If the main diagonal is zero, resort the matrix
if ( m[i][i] == 0.0 ){
for ( j = i+1; j < m.getRows(); j++ ){
if ( m[j][i] != 0.0 ){
// Add one row to other
for ( k = 0; k < m.getCols(); k++ ){
temp = m[i][k];
m[i][k] = m[j][k];
m[j][k] = temp;
}
// For Gauss-Jordan Elimination if we do a switch,
//the determinant switches sign.
detvalue = -detvalue;
break;
}
}
}
// If after resort the diagonal is still zero then the determinate
// is definately zero
// Pointless contining if det is already zero
if ( m[i][i] == 0.0 ){
return 0.0;
}
// We now elimiate the lower rows to obtain a triangle of zeros
for ( j = i+1; j < m.getRows(); j++ ){
if ( j != i ){
factor = ( m[j][i] * 1.0 ) / m[i][i];
// Add one row to the other
for ( k = i; k < m.getCols(); k++ ){
m[j][k]-=factor * m[i][k];
}
}
}
}
// Calculate the main diagonal
for ( i = 0; i < m.getRows(); i++ ){
detvalue *= m[i][i];
}
return detvalue;
}