Correctness isn't that hard to get. You just need to add a bitmap for exceptional values in all matrices. This bitmap can be accessed by sparse operations so that the iteration is across the union of non-zero elements in the sparse vector/matrix and exception elements in the operand.
That fact is, however, that preserving NaN results in these corner cases is not normally a huge priority for users. Deleting all support for sparse vectors, on the other hand, is a huge impact on utility of commons math. To my mind deleting hugely useful functionality in the face of a small issue is upside down, especially when there is actually a pretty simple fix available. On Sat, Dec 1, 2012 at 8:02 AM, Sébastien Brisard <sebastien.bris...@m4x.org > wrote: > A few months ago, we started a thread on this issue (on the users ML). It > got no answers! I am personally not happy with removing the support for > sparse vectors/matrices, but the truth is we didn't see a way to achieve > the same degree of correctness as --say-- array based matrices and vectors. > As far as I am concerned, though, this is still an open question, and if > you have ideas about these issues, we would be glad to here them! >
