Regarding Mauro's example: it is my understanding that your first example is that much faster mainly for cache reasons; indeed, the speed difference is less visible with the following two functions:
f1(n) = (b = Array(Float64, n); fill!(b, 0.0)) f2(n) = (b = zeros(Float64, n); fill!(b, 0.0)) Then f2 will be at most twice as slow, but often faster than that. Rafael
