blob: 72bead2a7aced8ca93f86fc088e883ddcf9c9748 [file] [log] [blame]
#include <iostream>
struct init {
init() { std::cout << "[init]\n"; }
};
init init_obj;
// [init]
#include <Eigen/Dense>
int main()
{
Eigen::MatrixXd A(2,2);
A << 2, -1, 1, 3;
std::cout << "Here is the input matrix A before decomposition:\n" << A << "\n";
std::cout << "[init]\n";
std::cout << "[declaration]\n";
Eigen::PartialPivLU<Eigen::Ref<Eigen::MatrixXd> > lu(A);
std::cout << "Here is the input matrix A after decomposition:\n" << A << "\n";
std::cout << "[declaration]\n";
std::cout << "[matrixLU]\n";
std::cout << "Here is the matrix storing the L and U factors:\n" << lu.matrixLU() << "\n";
std::cout << "[matrixLU]\n";
std::cout << "[solve]\n";
Eigen::MatrixXd A0(2,2); A0 << 2, -1, 1, 3;
Eigen::VectorXd b(2); b << 1, 2;
Eigen::VectorXd x = lu.solve(b);
std::cout << "Residual: " << (A0 * x - b).norm() << "\n";
std::cout << "[solve]\n";
std::cout << "[modifyA]\n";
A << 3, 4, -2, 1;
x = lu.solve(b);
std::cout << "Residual: " << (A0 * x - b).norm() << "\n";
std::cout << "[modifyA]\n";
std::cout << "[recompute]\n";
A0 = A; // save A
lu.compute(A);
x = lu.solve(b);
std::cout << "Residual: " << (A0 * x - b).norm() << "\n";
std::cout << "[recompute]\n";
std::cout << "[recompute_bis0]\n";
Eigen::MatrixXd A1(2,2);
A1 << 5,-2,3,4;
lu.compute(A1);
std::cout << "Here is the input matrix A1 after decomposition:\n" << A1 << "\n";
std::cout << "[recompute_bis0]\n";
std::cout << "[recompute_bis1]\n";
x = lu.solve(b);
std::cout << "Residual: " << (A1 * x - b).norm() << "\n";
std::cout << "[recompute_bis1]\n";
}