Squashed 'third_party/eigen/' content from commit 61d72f6
Change-Id: Iccc90fa0b55ab44037f018046d2fcffd90d9d025
git-subtree-dir: third_party/eigen
git-subtree-split: 61d72f6383cfa842868c53e30e087b0258177257
diff --git a/doc/examples/class_FixedBlock.cpp b/doc/examples/class_FixedBlock.cpp
new file mode 100644
index 0000000..9978b32
--- /dev/null
+++ b/doc/examples/class_FixedBlock.cpp
@@ -0,0 +1,27 @@
+#include <Eigen/Core>
+#include <iostream>
+using namespace Eigen;
+using namespace std;
+
+template<typename Derived>
+Eigen::Block<Derived, 2, 2>
+topLeft2x2Corner(MatrixBase<Derived>& m)
+{
+ return Eigen::Block<Derived, 2, 2>(m.derived(), 0, 0);
+}
+
+template<typename Derived>
+const Eigen::Block<const Derived, 2, 2>
+topLeft2x2Corner(const MatrixBase<Derived>& m)
+{
+ return Eigen::Block<const Derived, 2, 2>(m.derived(), 0, 0);
+}
+
+int main(int, char**)
+{
+ Matrix3d m = Matrix3d::Identity();
+ cout << topLeft2x2Corner(4*m) << endl; // calls the const version
+ topLeft2x2Corner(m) *= 2; // calls the non-const version
+ cout << "Now the matrix m is:" << endl << m << endl;
+ return 0;
+}