Fast and efficient coercion of standard matrix objects to sparse matrices. Borrowed from http://gallery.rcpp.org/articles/sparse-matrix-coercion/. INTERNAL USE ONLY.
as_dgCMatrix(XX_)
An object of class Matrix
that has a sparse structure
suitable for coercion to a sparse matrix format of dgCMatrix
.
An object of class dgCMatrix
, coerced from input XX_
.