import Math:all;
import Array:all;

int [.,.] matmult(int[.,.] A, int[.,.] B) {
  C = {[i,k] -> sum(A[[i,.]] * B[[.,k]])}; 

  return(C);
}

int main() {
  A = with([0,0] <= iv = [i,j] < [1000,1000]) 
      genarray([1000,1000], i+j);   

  C = matmult(A,A);
  return (C[[0,0]]);
}