From 3cd2a125b2712d6b7c620bef0671c6a05839d6e5 Mon Sep 17 00:00:00 2001
From: Benoit Jacob <jacob.benoit.1@gmail.com>
Date: Mon, 24 Dec 2007 11:14:25 +0000
Subject: - rework the coefficients API - make vectors use a separate loop
 unroller, so that copying a row-vector into a col-vector is now possible -
 add much more documentation - misc improvements

---
 doc/examples/class_Block.cpp | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 doc/examples/class_Block.cpp

(limited to 'doc/examples/class_Block.cpp')

diff --git a/doc/examples/class_Block.cpp b/doc/examples/class_Block.cpp
new file mode 100644
index 000000000..17dc4bce1
--- /dev/null
+++ b/doc/examples/class_Block.cpp
@@ -0,0 +1,23 @@
+#include <Eigen/Core.h>
+USING_PART_OF_NAMESPACE_EIGEN
+using namespace std;
+
+template<typename Scalar, typename Derived>
+Eigen::Block<Derived, 2, 2>
+topLeft2x2Corner(MatrixBase<Scalar, Derived>& m)
+{
+  return Eigen::Block<Derived, 2, 2>(m.ref(), 0, 0);
+  // note: tempting as it is, writing "m.block<2,2>(0,0)" here
+  // causes a compile error with g++ 4.2, apparently due to
+  // g++ getting confused by the many template types and
+  // template arguments involved.
+}
+
+int main(int, char**)
+{
+  Matrix3d m = Matrix3d::identity();
+  cout << topLeft2x2Corner(m) << endl;
+  topLeft2x2Corner(m) *= 2;
+  cout << "Now the matrix m is:" << endl << m << endl;
+  return 0;
+}
-- 
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