Hi Andy,

I adopted the heuristic from Leon Bottou's sgd implementation (version
1.3). He explains the heuristic in [1] - search for "Choosing the Gain
Schedule". I'm not aware of any paper which describes the rational in
more depth.

Here's the quote from the slide: "Choose t_0 to make sure that the
expected initial updates are comparable with the expected size of the
weights. "

[1] http://istcolloq.gsfc.nasa.gov/fall2009/presentations/bottou.pdf

2011/11/22 Andreas Müller <[email protected]>:
> Hi everybody.
> [..]
> I thought the initial learning rate in sgd is choosen using
> a subset of the training set. This seems to be in
> contradiction to using the heuristic.

That would be a great feature indeed. Any volunteers :-)

>
> Also, I think there is a typo in the doc where they
> explain the learning rate schedule.
> In 3.3.6.1 SGD, below the formular fo the schedule,
> it says "t_0 is the time step [...], t_0 is choosen
> automatically". I think the first "t_0" should
> actually be "t". Is that right?

You are absolutely right - the description is messed up in various
ways... it should be "eta^{(t)} is given by 1.0 / (\alpha * (t_0 + t))
where t_0 is determined using the following heuristic (insert
heuristic)"
I'll fix that ASAP!

thanks,
 Peter

>
> Any help would be appreciated!
>
> Thanks,
> Andy
>
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-- 
Peter Prettenhofer

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