Squashed 'third_party/eigen/' changes from 61d72f6..cf794d3
Change-Id: I9b814151b01f49af6337a8605d0c42a3a1ed4c72
git-subtree-dir: third_party/eigen
git-subtree-split: cf794d3b741a6278df169e58461f8529f43bce5d
diff --git a/doc/examples/make_circulant2.cpp b/doc/examples/make_circulant2.cpp
new file mode 100644
index 0000000..95d3dd3
--- /dev/null
+++ b/doc/examples/make_circulant2.cpp
@@ -0,0 +1,52 @@
+#include <Eigen/Core>
+#include <iostream>
+
+using namespace Eigen;
+
+// [circulant_func]
+template<class ArgType>
+class circulant_functor {
+ const ArgType &m_vec;
+public:
+ circulant_functor(const ArgType& arg) : m_vec(arg) {}
+
+ const typename ArgType::Scalar& operator() (Index row, Index col) const {
+ Index index = row - col;
+ if (index < 0) index += m_vec.size();
+ return m_vec(index);
+ }
+};
+// [circulant_func]
+
+// [square]
+template<class ArgType>
+struct circulant_helper {
+ typedef Matrix<typename ArgType::Scalar,
+ ArgType::SizeAtCompileTime,
+ ArgType::SizeAtCompileTime,
+ ColMajor,
+ ArgType::MaxSizeAtCompileTime,
+ ArgType::MaxSizeAtCompileTime> MatrixType;
+};
+// [square]
+
+// [makeCirculant]
+template <class ArgType>
+CwiseNullaryOp<circulant_functor<ArgType>, typename circulant_helper<ArgType>::MatrixType>
+makeCirculant(const Eigen::MatrixBase<ArgType>& arg)
+{
+ typedef typename circulant_helper<ArgType>::MatrixType MatrixType;
+ return MatrixType::NullaryExpr(arg.size(), arg.size(), circulant_functor<ArgType>(arg.derived()));
+}
+// [makeCirculant]
+
+// [main]
+int main()
+{
+ Eigen::VectorXd vec(4);
+ vec << 1, 2, 4, 8;
+ Eigen::MatrixXd mat;
+ mat = makeCirculant(vec);
+ std::cout << mat << std::endl;
+}
+// [main]