# How to take log of sum product of matrix and e ^ x?

I wonder how to take the record of this sum function where it has $$e$$ inside

$$f (x) = sum_ {ij} (V_ {ij} e ^ {(x-N_ {ij}) ^ 2})$$

where $$V_ {ij}$$ Y $$N_ {ij}$$ are the size of the matrix $$i times j$$