template<typename XprType, typename RowIndices, typename ColIndices>
class Eigen::IndexedView< XprType, RowIndices, ColIndices >

Expression of a non-sequential sub-matrix defined by arbitrary sequences of row and column indices.

Template Parameters

XprType	the type of the expression in which we are taking the intersections of sub-rows and sub-columns
RowIndices	the type of the object defining the sequence of row indices
ColIndices	the type of the object defining the sequence of column indices

This class represents an expression of a sub-matrix (or sub-vector) defined as the intersection of sub-sets of rows and columns, that are themself defined by generic sequences of row indices \( \{r_0,r_1,..r_{m-1}\} \) and column indices \( \{c_0,c_1,..c_{n-1} \}\). Let \( A \) be the nested matrix, then the resulting matrix \( B \) has m rows and n columns, and its entries are given by: \( B(i,j) = A(r_i,c_j) \).

The RowIndices and ColIndices types must be compatible with the following API:

<integral type> operator[](Index) const;
Index size() const;

Typical supported types thus include:

• std::vector<int>
• std::valarray<int>
• std::array<int>
• Plain C arrays: int[N]
• Eigen::ArrayXi
• decltype(ArrayXi::LinSpaced(...))
• Any view/expressions of the previous types
• Eigen::ArithmeticSequence
• Eigen::internal::AllRange (helper for Eigen::all)
• Eigen::internal::SingleRange (helper for single index)
• etc.

In typical usages of Eigen, this class should never be used directly. It is the return type of DenseBase::operator()(const RowIndices&, const ColIndices&).

See also

class Block