On Thu, Feb 27, 2014 at 7:01 PM, Andrew Musselman < [email protected]> wrote:
> > And I'm not sure if this is what Dmitriy meant in his comments (3), but I'd > love to be able to do Mathematica-style work in an interactive shell and/or > symbolic system where I could do A*B' and it just worked. That would crush > everything on the market, though it could be a lot of work to build a DSL > that supports it. > Actually, I've already had that in one incarnation and now rewriting it for the second time -- check out WIP in https://issues.apache.org/jira/browse/MAHOUT-1346 . My previous implementation ended up not lending itself well to physical plan rewrites, so i rolled it back and started over. DSL itself is not so much a problem. Optimizer rules are somewhat a problem. E.g. in SSVD there's a part that deals with skinny matrix multiplication. There're also some decisions i am not sure about -- like a thing about row keying in Mahout DRM which generally doesn't have to be row index and which doesn't play well with some of rewrites -- but SSVD in general allows non-integer row keying for A and U matrices, so there are questions of how to isolate those issues architecturally from pure linear algebra in matrices etc.
