Eigen_求秩

rank()基本用法

JacobiSVD<MatrixXd> svd(m);
svd.rank()

#include <iostream>
#include <cstring>
#include "Eigen/Dense"
using namespace std;
using namespace Eigen;
int main()
{
    MatrixXd a(3, 3);
    a << 1,  2, 0,
         3, -1, 1,
         0,  2, 0;

    MatrixXd b(3, 1);
    b << 2,
        1,
        1;
    MatrixXd m = MatrixXd::Zero(3, 3);
    m.col(0) = b;
    m.col(1) = a * b;
    m.col(2) = a * a * b;
    cout << m << endl;
    JacobiSVD<MatrixXd> svd(m);
    cout << svd.rank() << endl;
}