improved speed through adding multiple parallel operations

[eweine]

No description provided.

[pcarbo]

@eweine This looks great. If I understand correctly, you have sped up two functions, "cost" and "poisson_nmf_kkt". Can I request a couple small changes:

(1) In cost(), add a third setting for "version", and call it "Rcpp_parallel", and then we can easily compare version = "Rcpp" vs. version = "Rcpp_parallel" to check that they produce the same result.

(2) Similarly, in poisson_nmf_kkt() please add a "version" argument with two settings, "Rcpp" and "Rcpp_parallel".

Thanks!

[eweine]

@pcarbo yes, those are the two functions that I have sped up by making parallel.

I added a third version for cost and poisson_nmf_kkt, and added a few tests to confirm that the results are equivalent between version Rcpp and Rcpp_parallel