Accuracy changes even when learning rate is set to zero

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Suraj Srinivas

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Jun 1, 2015, 5:40:38 AM6/1/15
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Hello all,

While finetuning a model, I noticed a curious thing - even when I set all the blobs_lr and weight_decay parameters to 0 for all layers, the loss and accuracy still change. After simply having run it for about 5k iterations, I noticed that the accuracy wasn't changing much from the initial value.

Intial acc = 64.2 %
After 1k iterations = 63.55%
After 2k iterations = 63.7%
After 3k = 64%
After 4k = 63.7% ...etc.

I even removed dropout and checked - no change in behaviour.
Has anyone encountered this kind of behaviour before? If so, can anyone tell me why this may be happening?

Evan Shelhamer

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Jun 1, 2015, 1:36:30 PM6/1/15
to Suraj Srinivas, caffe...@googlegroups.com
The momentum is independent of the learning rate. If you are resuming from a solverstate the old momentum will keep having an effect until it vanishes. This is a bit of a corner case, but that's what the standard update equation gives.

That or you're running on different subsets of your test data, which might be the case if it keeps oscillating.
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Suraj Srinivas

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Jun 2, 2015, 1:59:25 AM6/2/15
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Thanks for your response!
I am not entirely sure how it works. So if I delete the solverstate file then the momentum information would also be deleted, so if I finetune after that will it ensure that this effect is nullified?
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