If factors = "default", the factors and
loadings are both unconstrained. If factors = "nonneg", the
factors are constrained to be non-negative, and the loadings are
unconstrained.
subset
Data samples (rows) used to estimate the
covariances. Sset to NULL to use all the data.
remove_singleton
If remove_singleton = TRUE, factors
corresponding to singleton matrices will be removed from the output.
tag
How to name the covariance matrices.
output_model
The fitted flash model will be saved to this file
(using saveRDS).
greedy_args
List containing additional parameters passed to
flashier::flash_greedy.
backfit_args
List containing additional parameters passed
to flashier::flash_backfit.