Large loops in R

Dear Michael,

Thank you for your answer.

I have 2 matrices. Each position of the matrices is a weight. And I
need to calculate the following sum of differences:

Considering:
mat1 and mat2 - two matrices (each of them 48000 x 48000).
d1 and d2 - two constant values.

sum<-0;
for(i in 1:nrows1){
                        for(j in 1:nrows2){
                                        sum<-sum+ ( ( (mat1(i,j)/d1) -
(mat2(i,j)/d2) )^2 )
                                }
                        }
                }

I was wondering if there is a better way to do this sum.