9   Eigen::Matrix4f m4 = Eigen::Matrix4f::Identity();  in main()  local
11   std::cout << "*** Step 1 ***\nm3:\n" << m3 << "\nm4:\n" << m4 << std::endl;  in main()
14   m4.setZero();  in main()
17   std::cout << "*** Step 2 ***\nm3:\n" << m3 << "\nm4:\n" << m4 << std::endl;  in main()
20   m4.block<3,3>(0,1) = m3;  in main()
21   m3.row(2) = m4.block<1,3>(2,0);  in main()
23   std::cout << "*** Step 3 ***\nm3:\n" << m3 << "\nm4:\n" << m4 << std::endl;  in main()
28     m4.block(0,1,3,3).setIdentity();  in main()
29     std::cout << "*** Step 4 ***\nm4:\n" << m4 << std::endl;  in main()
33   m4.diagonal().block(1,2).setOnes();  in main()
34   std::cout << "*** Step 5 ***\nm4.diagonal():\n" << m4.diagonal() << std::endl;  in main()
35   std::cout << "m4.diagonal().start(3)\n" << m4.diagonal().start(3) << std::endl;  in main()
38   m4 = m4.cwise()*m4;  in main()
40   std::cout << "*** Step 6 ***\nm3:\n" << m3 << "\nm4:\n" << m4 << std::endl;  in main()
43   std::cout << "*** Step 7 ***\n m4.sum(): " << m4.sum() << std::endl;  in main()
44   std::cout << "m4.col(2).sum(): " << m4.col(2).sum() << std::endl;  in main()
45   std::cout << "m4.colwise().sum():\n" << m4.colwise().sum() << std::endl;  in main()
46   std::cout << "m4.rowwise().sum():\n" << m4.rowwise().sum() << std::endl;  in main()
49   m4 = m4 * m4; // auto-evaluates so no aliasing problem (performance penalty is low)  in main()
50   Eigen::Matrix4f other = (m4 * m4).lazy(); // forces lazy evaluation  in main()
51   m4 = m4 + m4; // here Eigen goes for lazy evaluation, as with most expressions  in main()
52   m4 = -m4 + m4 + 5 * m4; // same here, Eigen chooses lazy evaluation for all that.  in main()
53   m4 = m4 * (m4 + m4); // here Eigen chooses to first evaluate m4 + m4 into a temporary.  in main()
55   m3 = m3 * m4.block<3,3>(1,1); // here Eigen chooses NOT to evaluate block() into a temporary  in main()
58   m4 = m4 * m4.transpose(); // same here, lazy evaluation of the transpose.  in main()
59   m4 = m4 * m4.transpose().eval(); // forces immediate evaluation of the transpose  in main()
61   std::cout << "*** Step 8 ***\nm3:\n" << m3 << "\nm4:\n" << m4 << std::endl;  in main()