Quick check that sum of positive values is at most threshold

New to Julia
5

This is type-unstable. Your s starts as an integer but ends up as a floating-point value (for floating-point arrays). (See the performance tips.)

If you fix this, it is as fast as sum (actually slightly faster because it avoids the slight overhead of pairwise summation):

julia> function mysum(a)
           s = zero(eltype(a))
           @simd for i in eachindex(a)
               s += a[i]
           end
           return s
       end
mysum (generic function with 1 method)

julia> a = rand(1000); @btime sum($a); @btime mysum($a);
  97.765 ns (0 allocations: 0 bytes)
  93.361 ns (0 allocations: 0 bytes)

(The @inbounds is inferred here, though it wouldn’t hurt to add it.)

It probably won’t help if you have the s > a check in every loop iteration, but it will help if you do the loop in chunks.

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