Hi,

I have two similar functions, for training a Boltzmann machine. Here’s the first:

```
function train(ptrns, n_h, ϵ, n_G_s, steps)
w = rand(Normal(0,0.01),size(ptrns,2)+1, n_h+1)
h = hcat(zeros(1,n_h),1);
hidden_activation = zeros(size(ptrns,1),steps, n_h+1)
visible_reconstructions = zeros(size(ptrns,1), steps, size(ptrns,2)+1)
proportions = dropdims(mean(ptrns, dims=1), dims=1);
visible_biases = log.(proportions./(1 .- proportions));
w[end,1:end-1] = zeros(n_h)
w[1:end-1,end] = visible_biases
w[end,end] = 0
fantasy_visible = vcat(zeros(size(ptrns,2)),1)
fantasy_hidden = vcat(zeros(n_h),1)
for i in 1:steps
v = hcat(copy(ptrns),ones(size(ptrns,1)));
for pt in 1:size(v,1)
for unts in 1:n_h
h[unts] = 1/(1+exp(-(v[pt,:]'*w[:,unts])))
end
w[end,end] = 0
for s in 1:n_G_s
for unts in 1:n_h
p = 1/(1+exp(-(fantasy_visible'*w[:,unts])))
fantasy_hidden[unts] = rand(Bernoulli(p))
end
end
for unts in 1:(size(v,2)-1)
p = 1/(1+exp(-(fantasy_hidden'*w[unts,:])))
fantasy_visible[unts] = rand(Bernoulli(p))
end
end
w = w + ϵ*(v[pt,:]*h) - ϵ*(fantasy_visible*fantasy_hidden')
w[end,end] = 0
hidden_activation[pt,i,:] = h
visible_reconstructions[pt,i,:] = v[pt,:]
end
end
return w , hidden_activation, visible_reconstructions
end;
```

and I get the following error:

```
UndefVarError: w not defined
Stacktrace:
[1] top-level scope at In[1]:37
```

You can see that I defined `w`

at the beginning of the function, and still Julia complains about `w`

not being defined. What’s bothering me is that I don’t get any error in the following similar function:

```
function train(ptrns, n_h, ϵ, n_G_s, steps)
w = rand(Normal(0,0.01),size(ptrns,2)+1, n_h+1)
h = hcat(zeros(1,n_h),1);
hidden_activation = zeros(size(ptrns,1),steps, n_h+1)
visible_reconstructions = zeros(size(ptrns,1), steps, size(ptrns,2)+1)
proportions = dropdims(mean(ptrns, dims=1), dims=1);
visible_biases = log.(proportions./(1 .- proportions));
w[end,1:end-1] = zeros(n_h)
w[1:end-1,end] = visible_biases
w[end,end] = 0
for i in 1:steps
v = hcat(copy(ptrns),ones(size(ptrns,1)));
for pt in 1:size(v,1)
for unts in 1:n_h
p = 1/(1+exp(-(v[pt,:]'*w[:,unts])))
h[unts] = rand(Bernoulli(p))
end
w = w + ϵ*(v[pt,:]*h)
w[end,end] = 0
for s in 1:n_G_s
for unts in 1:(size(v,2)-1)
p = 1/(1+exp(-((h*w'[:,unts])[1])))
v[pt,unts] = p
end
for unts in 1:n_h
p = 1/(1+exp(-(v[pt,:]'*w[:,unts])))
if s == n_G_s
h[unts] = p
else
h[unts] = rand(Bernoulli(p))
end
end
end
w = w - ϵ*(v[pt,:]*h)
w[end,end] = 0
hidden_activation[pt,i,:] = h
visible_reconstructions[pt,i,:] = v[pt,:]
end
end
return w , hidden_activation, visible_reconstructions
end;
```

This function has the same structure as the previous one, yet it runs without any error. What’s the problem? Does it have something to do with scope of variables? If it does, why does the second function runs normally, and how to fix the first function?

Thanks in advance!