ction values
corresponding to the Poisson non-negative matrix factorization are
computed; if <code>model = "multinom"</code>, the multinomial topic model
loss function values are returned.</p></dd>
<dt>version</dt>
<dd><p>When <code>version == "R"</code>, the computations are
performed entirely in R; when <code>version == "Rcpp"</code>, an Rcpp
implementation is used. The R version is typically faster when
<code>X</code> is a dense matrix, whereas the Rcpp version is faster and
more memory-efficient when <c