= 3;
int cols = 4;
MatrixXf x;
x = MatrixXf::Zero(rows, cols);
cout << x << endl << endl;...x = MatrixXf::Ones(rows, cols);
cout << x << endl << endl;
x = MatrixXf::Constant(rows, cols, value...x = MatrixXf::Random(rows, cols);
cout << x << endl << endl;
x.setZero(rows, cols);
cout << x <...< endl << endl;
x.setOnes(rows, cols);
cout << x << endl << endl;
x.setConstant(rows, cols, value...=5, cols=5;
MatrixXf m(rows,cols);
m << (Matrix3f() << 1, 2, 3, 4, 5, 6, 7, 8, 9).finished(),//左上角