Re: Contributing to MLlib on GLM

2014-06-28 Thread xwei
Hi Gang, No worries! I agree LBFGS would converge faster and your test suite is more comprehensive. I'd like to merge my branch with yours. I also agree with your viewpoint on the redundancy issue. For different GLMs, usually they only differ in gradient calculation but the regression.sca

Re: Linear CG solver

2014-06-28 Thread Evan Sparks
Hey, We're actually working on similar ideas in the AMPlab with spark - for example we've got some image classification pipelines built on this idea - http://www.eecs.berkeley.edu/~brecht/papers/07.rah.rec.nips.pdf Approximating kernel methods via random projections hit with nonlinearity. Add

Re: Linear CG solver

2014-06-28 Thread Debasish Das
Thanks Tom for the pointers... I have a IPM running on the JVM which uses SOCP formulation for the quadratic program I wrote above We are going to show the details of it at the SummitIPM runtimes and accuracy give a baseline for the problem that we are solving... Now we are trying to see how

Re: Linear CG solver

2014-06-28 Thread Tom Vacek
What is your general solver? IPM or simplex or something else? I have seen a lot of attempts to apply iterative solvers for the subproblems on those without much luck because the conditioning of the linear systems gets worse and worse near the optimum. IPOPT (interior point method) has an LBFGS

Re: Linear CG solver

2014-06-28 Thread Debasish Das
Hi, I am coming up with an iterative solver for Equality and bound constrained quadratic minimization... I have the cholesky versions running but cholesky does not scale for large dimensions but works fine for matrix factorization use-cases where ranks are low.. Minimize 0.5x'Px + q'x s.t Aeq x

Re: Linear CG solver

2014-06-28 Thread Tom Vacek
What flavor of SVM are you trying to support? LSSVM doesn't need a bound constraint, but most other formulations do. There have been ideas for bound-constrained CG, though bounded LBFGS is more common. I think code for Nystrom approximations or kernel mappings would be more useful. On Fri, Jun

Re: Spark Matrix Factorization

2014-06-28 Thread Krakna H
Hi Deb, Putting your code on github will be much appreciated -- it will give us a good starting point to adapt for our purposes. Regards. On Sat, Jun 28, 2014 at 10:57 AM, Debasish Das [via Apache Spark Developers List] wrote: > Factorization problems are non-convex and so both ALS and DSGD w

Re: Spark Matrix Factorization

2014-06-28 Thread Debasish Das
Factorization problems are non-convex and so both ALS and DSGD will converge to local minima and it is not clear which minima will be better than the other until we run both the algorithms and see... So I will still say get a DSGD version running in the test setup while you experiment with the Spa

Re: Spark Matrix Factorization

2014-06-28 Thread Krakna H
Hi Deb, Thanks so much for your response! At this point, we haven't determined which of DSGD/ALS to go with and were waiting on guidance like yours to tell us what the right option would be. It looks like ALS seems to be good enough for our purposes. Regards. On Fri, Jun 27, 2014 at 12:47 PM, D