fastmath_example.jl

function sum_diff_fast(x)
                 n=length(x); d = 1/(n-1)
                 s = zero(eltype(x))
                 @fastmath s = s +  (x[2] - x[1]) / d
                 @fastmath for i = 2:n-1
                       s =  s + (x[i+1] - x[i+1]) / (2*d)
                 end
                 @fastmath s = s + (x[n] - x[n-1])/d

         end

function sum_diff(x)
                 n = length(x); d = 1/(n-1)
                 s = zero(eltype(x))
                 s = s +  (x[2] - x[1]) / d
                 for i = 2:length(x)-1
                       s =  s + (x[i+1] - x[i+1]) / (2*d)
                 end
                 s = s + (x[n] - x[n-1])/d
              end