1 2namespace Eigen { 3 4/** 5 6\eigenManualPage MatrixfreeSolverExample Matrix-free solvers 7 8Iterative solvers such as ConjugateGradient and BiCGSTAB can be used in a matrix free context. To this end, user must provide a wrapper class inheriting EigenBase<> and implementing the following methods: 9 - \c Index \c rows() and \c Index \c cols(): returns number of rows and columns respectively 10 - \c operator* with your type and an %Eigen dense column vector (its actual implementation goes in a specialization of the internal::generic_product_impl class) 11 12\c Eigen::internal::traits<> must also be specialized for the wrapper type. 13 14Here is a complete example wrapping an Eigen::SparseMatrix: 15\include matrixfree_cg.cpp 16Output: \verbinclude matrixfree_cg.out 17 18*/ 19 20}