doc/snippets/TopicAliasing_block_correct.cpp - eigen - Git at Google

 MatrixXi mat(3, 3);
 mat << 1, 2, 3, 4, 5, 6, 7, 8, 9;
 cout << "Here is the matrix mat:\n" << mat << endl;

 // The eval() solves the aliasing problem
 mat.bottomRightCorner(2, 2) = mat.topLeftCorner(2, 2).eval();
 cout << "After the assignment, mat = \n" << mat << endl;
	MatrixXi mat(3, 3);
	mat << 1, 2, 3, 4, 5, 6, 7, 8, 9;
	cout << "Here is the matrix mat:\n" << mat << endl;

	// The eval() solves the aliasing problem
	mat.bottomRightCorner(2, 2) = mat.topLeftCorner(2, 2).eval();
	cout << "After the assignment, mat = \n" << mat << endl;