optimize 2D array in C++
- by Hristo
I'm dealing with a 2D array with the following characteristics:
const int cols = 500;
const int rows = 100;
int arr[rows][cols];
I access array arr in the following manner to do some work:
for(int k = 0; k < T; ++k) { // for each trainee
myscore[k] = 0;
for(int i = 0; i < N; ++i) { // for each sample
for(int j = 0; j < E[i]; ++j) { // for each expert
myscore[k] += delta(i, anotherArray[k][i], arr[j][i]);
}
}
}
So I am worried about the array 'arr' and not the other one. I need to make this more cache-friendly and also boost the speed. I was thinking perhaps transposing the array but I wasn't sure how to do that. My implementation turns out to only work for square matrices. How would I make it work for non-square matrices?
Also, would mapping the 2D array into a 1D array boost the performance? If so, how would I do that? Finally, any other advice on how else I can optimize this... I've run out of ideas, but I know that arr[j][i] is the place where I need to make changes because I'm accessing columns by columns instead of rows by rows so that is not cache friendly at all.
Thanks,
Hristo
