momentum update for embeddings

[ashwinkalyan]

Hello,

I am trying to get an embedding working similar to NNLM example provided. The architecture is as given below:

vs = 150
es = 150
cs = 3
hs = es*cs
-- define model
hu = nn.Sequential()
hu:extend(
  nn.LookupTable(vs,es),
  nn.Collapse(2)
)
hu:add(nn.Linear(hs,hs))
hu:add(nn.Tanh())
hu:add(nn.Linear(hs,vs))
hu:add(nn.LogSoftMax())

I am optimizing this in a naive manner without using the optimizer class provided as:
for i=1,100 do -- #x do
    p = hu:forward(x[i])
    t = y[i]
    err = criterion:forward(p,t)
    g = criterion:backward(p,t)
    hu:backward(x[i],g)
     -- NOT WORKING hu:updateGradParameters(nu)
    hu:updateParameters(lr)
    hu:zeroGradParameters()
end

When I do the backward pass, I get
[torch.DoubleTensor with no dimension]

and hence, I think I am not able to update the grad params with the momentum.

Any suggestions?

[nicholas-leonard]

@AshwinKalyanV Hi. What criterion are you using, what is the size of x and y, and what is the full stack trace of the error?