[pdp-discuss] Leabra: learning continous values over time?

[Randall C. O'Reilly]

Frank,

The parameters on the scalar val layer are important (as you discovered).  I 
did a fair bit of testing with special projects that exercise the system 
pretty well, avail at:

ftp://grey.colorado.edu/pub/oreilly/misc/gaus22_scalar_test_01.proj.gz
and loc_scalar_test_05.proj.gz

both use the wt_sig = gain,off = 1.0, 1.0, as you discovered, and perhaps some 
other special params that might want to check out.

the loc guy is used for representing 0-1 values with only 3 units (0, .5, 1), 
which we use in our PVLV model.

As for the nothing question: excellent point and currently it is not 
supported.  need to add that functionality.  given the way things work, with 
only a floating point number to go on, I guess we would just have the spec 
have a magic number that you enter that is the signal for nothing, and when 
the input has that, it does that.  

I will put this in pdp++ 4.0 -- not sure I'll back-port it but could if you 
really want it now..

- Randy

On Wednesday 31 January 2007 11:52, Frank Leoné wrote:
> Hi all,
>
> Again I want to expres my gratitude: it now works! Especially this, for me
> previous undiscovered, layertype really opens new interesting
> possibilities, I like it!
>
> It does not work flawlessly though: the error first goes down quite fast,
> but after some time rises even faster, to really high levels, just to go
> down again (not as far down as it went previously) and to rise later on,
> etcetera. Needles to say, it is quite hard to reach low error levels with
> this kind of behaviour. Does anyone got an idea what the reason might be?
> I'm using a leabra network with a context layer (made with the wizard).
>
> Also I have one other minor problem: for the learning over time I want the
> retinal input to switch off after the first trial. So, the first trial the
> input is a value between a minimum and a maximum, converted in a
> distributed code. But in the rest of the trials no such input should be
> given: the input layer should give a zero input. But if I enter zero as
> input, it is converted to the center of my distributed code, which is
> ofcourse normally the correct behavior. So I thought: lets take a number
> far outside the borders, but that point is just moved to the border itself.
>
> So: how can I input nothing into a scalarvallayer? I now fixed it by just
> clamping the entire pattern, but it would be nice to use the scalarvallayer
> again.
>
> Thanks in advance!
>
> Frank
>
> PS. I can't seem to reach the latest archives. Is there something wrong or
> is it just me? :)
>
> _________________________________________________________________
> Hotmail en Messenger on the move http://www.msn.nl/services
>
> _______________________________________________
> PDP-Discuss mailing list
> PDP-Discuss at psych.Colorado.EDU
> http://psych.colorado.edu/mailman/listinfo/pdp-discuss