Module refit 

Fixed-factor NNLS refits. Solves for one factor while the other is frozen, which is what a consensus NMF needs once the consensus factor has been assembled from the clustered restarts.

Freezing a factor makes both of its data products constant, so W^T V (or V H^T) is computed once up front rather than once per iteration. That is the expensive part of a HALS sweep, so a refit is far cheaper than a full solve of the same iteration count.

Functions

nmf_refit_h

Refit H against a frozen W.

nmf_refit_w

Refit W against a frozen H.