Polyhedron/external/eigen-3.4.0/doc/snippets/MatrixBase_reshaped_fixed.cpp

Matrix4i m = Matrix4i::Random();
cout << "Here is the matrix m:" << endl << m << endl;
cout << "Here is m.reshaped(fix<2>,fix<8>):" << endl << m.reshaped(fix<2>,fix<8>) << endl;