1 SparseMatrix<double> A(3,3); 2 A.insert(1,2) = 0; 3 A.insert(0,1) = 1; 4 A.insert(2,0) = 2; 5 A.makeCompressed(); 6 cout << "The matrix A is:" << endl << MatrixXd(A) << endl; 7 cout << "it has " << A.nonZeros() << " stored non zero coefficients that are: " << A.coeffs().transpose() << endl; 8 A.coeffs() += 10; 9 cout << "After adding 10 to every stored non zero coefficient, the matrix A is:" << endl << MatrixXd(A) << endl; 10