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/nullary_indexing.cpp b/doc/examples/nullary_indexing.cpp
new file mode 100644
index 0000000..e27c358
--- /dev/null
+++ b/doc/examples/nullary_indexing.cpp
@@ -0,0 +1,66 @@
+#include <Eigen/Core>
+#include <iostream>
+
+using namespace Eigen;
+
+// [functor]
+template<class ArgType, class RowIndexType, class ColIndexType>
+class indexing_functor {
+ const ArgType &m_arg;
+ const RowIndexType &m_rowIndices;
+ const ColIndexType &m_colIndices;
+public:
+ typedef Matrix<typename ArgType::Scalar,
+ RowIndexType::SizeAtCompileTime,
+ ColIndexType::SizeAtCompileTime,
+ ArgType::Flags&RowMajorBit?RowMajor:ColMajor,
+ RowIndexType::MaxSizeAtCompileTime,
+ ColIndexType::MaxSizeAtCompileTime> MatrixType;
+
+ indexing_functor(const ArgType& arg, const RowIndexType& row_indices, const ColIndexType& col_indices)
+ : m_arg(arg), m_rowIndices(row_indices), m_colIndices(col_indices)
+ {}
+
+ const typename ArgType::Scalar& operator() (Index row, Index col) const {
+ return m_arg(m_rowIndices[row], m_colIndices[col]);
+ }
+};
+// [functor]
+
+// [function]
+template <class ArgType, class RowIndexType, class ColIndexType>
+CwiseNullaryOp<indexing_functor<ArgType,RowIndexType,ColIndexType>, typename indexing_functor<ArgType,RowIndexType,ColIndexType>::MatrixType>
+indexing(const Eigen::MatrixBase<ArgType>& arg, const RowIndexType& row_indices, const ColIndexType& col_indices)
+{
+ typedef indexing_functor<ArgType,RowIndexType,ColIndexType> Func;
+ typedef typename Func::MatrixType MatrixType;
+ return MatrixType::NullaryExpr(row_indices.size(), col_indices.size(), Func(arg.derived(), row_indices, col_indices));
+}
+// [function]
+
+
+int main()
+{
+ std::cout << "[main1]\n";
+ Eigen::MatrixXi A = Eigen::MatrixXi::Random(4,4);
+ Array3i ri(1,2,1);
+ ArrayXi ci(6); ci << 3,2,1,0,0,2;
+ Eigen::MatrixXi B = indexing(A, ri, ci);
+ std::cout << "A =" << std::endl;
+ std::cout << A << std::endl << std::endl;
+ std::cout << "A([" << ri.transpose() << "], [" << ci.transpose() << "]) =" << std::endl;
+ std::cout << B << std::endl;
+ std::cout << "[main1]\n";
+
+ std::cout << "[main2]\n";
+ B = indexing(A, ri+1, ci);
+ std::cout << "A(ri+1,ci) =" << std::endl;
+ std::cout << B << std::endl << std::endl;
+#if __cplusplus >= 201103L
+ B = indexing(A, ArrayXi::LinSpaced(13,0,12).unaryExpr([](int x){return x%4;}), ArrayXi::LinSpaced(4,0,3));
+ std::cout << "A(ArrayXi::LinSpaced(13,0,12).unaryExpr([](int x){return x%4;}), ArrayXi::LinSpaced(4,0,3)) =" << std::endl;
+ std::cout << B << std::endl << std::endl;
+#endif
+ std::cout << "[main2]\n";
+}
+