void QRDecomposition<T>::operator()(const AbstractMatrix<T>& aMatrix) { q = DenseMatrix<T>(aMatrix.numRows(), aMatrix.numRows()); r = UpperTriangularMatrix<T>(aMatrix.numRows()); T normResult; TwoNorm<T> norm; for(int i = 0; i < aMatrix.numRows(); i++) { for(int j = 0; j < aMatrix.numRows(); j++) { q(i, j) = 0; r(i, j) = 0; } } for(int i = 0; i < aMatrix.numRows(); i++) { if(i == 0) { normResult = norm(aMatrix.getColumn(0)); if(normResult == 0) { throw std::domain_error("Error in QRDecomposition: Attempted division by zero"); } for(int j = 0; j < aMatrix.numRows(); j++) { q(j, 0) = aMatrix(j, 0) * (1 / normResult); } } else { Vector<T> temp(aMatrix.numRows()); temp = r(0, i) * q.getColumn(0); for(int k = 1; k < i; k++) { temp += r(k, i) * q.getColumn(k); } temp = aMatrix.getColumn(i) - temp; r(i, i) = norm(temp); if(r(i, i) == 0) { throw std::domain_error("QRDecomposition: Attempted division by zero"); } for(int j = 0; j < aMatrix.numRows(); j++) { q(j, i) = (1 / r(i, i)) * temp[j]; } } for(int j = 0; j < aMatrix.numRows(); j++) { r(i, j) = aMatrix.getColumn(j) * q.getColumn(i); } } }