2011/11/4 Andreas Müller <[email protected]>:
> My question is: has anyone started with a mlp implementation yet?

I was just working on one :)
I have the predict function for an arbitrary number of hidden layers
(classifier case) and some snippets of the RPROP algorithm. I've been
using weight vectors that come out of a Matlab implementation for now.

There used to be an MLP implementation in older versions (around 0.2,
I believe) but it was abandoned.

> My feature list would be:
> - online, minibatch and batch learning

I only need batch learning and classification for now... shall we keep
it simple?

> - vanilla gradient descent and rprop
> - l2 weight decay optional
> - tanh nonlinearities

Logistic activation functions seem fashionable; that's what Bishop and
other textbooks use. I'm not sure if there's a big difference, but it
seems to me that gradient computations might be slightly more
efficient (guesswork, I admit). We can always add a steepness
parameter later.

I've been reading the RPROP papers and it looks like IRPROP- is the
algorithm to go for; it's simple and not significantly worse than
RPROP+. We could look at the RPROP implementation in Wapiti (and maybe
even copy bits of it, it's MIT-licensed).

-- 
Lars Buitinck
Scientific programmer, ILPS
University of Amsterdam

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