At first: There is no evidence that vectorized code is faster in general.
If a build-in function can be applied to a complete array, a vectorization is much faster than a loop appraoch. When large temporary arrays are required, the benefits of the vectorization can be dominated by the expensive allocation of the memory, when it does not match into the processor cache.
A secondray effect of vectorizing is that the code looks more clear, at least as a rule of thumb. A trivial example:
% Loops:
A = rand(10);
B = rand(10);
C = zeros(size(A));
for i2 = 1:size(A, 2)
for i1 = 1:size(A, 1) % Columns in the inner loop
C(i1, i2) = A(i1, i2) + B(i1, i2);
end
end
% Vectorized:
C = A + B;
The 2nd method is faster concerning the runtime, but also for the programming and debug time. There is almost no chance to create a bug and it will be very easy to understand the code, when the program needs changes in the future.
