Which loop is faster?


for (I = 0; I < N; I++)
  for (J = 0; J < M; J++)
    update(Xs[I][J]);
or

for (I = 0; I < N; I++)
  for (J = 0; J < M; J++)
    update(Xs[J][I]);
???

>>34-36,38-41
You all need to learn some basic maths. You nitpick about size / 0 when that snippet of code isn't even going to cover half of the elements in that array.