The sole purpose of this namespace is to be able to import all functions and symbols that are expected to be used within operator() for indexing and slicing. If you already imported the whole Eigen namespace:
Namespace containing all symbols from the Eigen library.
Definition: B01_Experimental.dox:1
then you are already all set. Otherwise, if you don't want/cannot import the whole Eigen namespace, the following line:
is equivalent to:
using Eigen::placeholders::lastN;
static const Eigen::internal::all_t all
Definition: IndexedViewHelper.h:189
static const last_t last
Definition: IndexedViewHelper.h:44
static const auto lastp1
Definition: IndexedViewHelper.h:172
auto seq(FirstType f, LastType l, IncrType incr)
ArithmeticSequence< typename internal::cleanup_index_type< FirstType >::type, typename internal::cleanup_index_type< SizeType >::type, typename internal::cleanup_seq_incr< IncrType >::type > seqN(FirstType first, SizeType size, IncrType incr)
Definition: ArithmeticSequence.h:99