I tried these two functions to get the l2 regularization term for a NN model:

```
function ℓ₂(a)
s = zero(Float32)
for i in a
s += sum(i.^2)
end
s
end
```

```
function l₂(a)
s = zero(Float32)
Lₐ = length(a)
for i in 1:Lₐ
@inbounds Lᵢ = length(a[i])
for j in 1:Lᵢ
@inbounds s += a[i][j]^2
end
end
s
end
```

But I get different result, for the first function I get 469.8826f0 and for the second I get 469.87442f0.

Why this happens?

Moreover the second function is much slower than the first one. Why?

What is the best way to compute the sum of params of a model in julia?

Sorry for my english.