Julia Language Type Stability Write type-stable code
Example
function sumofsins1(n::Integer)
r = 0
for i in 1:n
r += sin(3.4)
end
return r
end
function sumofsins2(n::Integer)
r = 0.0
for i in 1:n
r += sin(3.4)
end
return r
end
Timing the above two functions shows major differences in terms of time and memory allocations.
julia> @time [sumofsins1(100_000) for i in 1:100];
0.638923 seconds (30.12 M allocations: 463.094 MB, 10.22% gc time)
julia> @time [sumofsins2(100_000) for i in 1:100];
0.163931 seconds (13.60 k allocations: 611.350 KB)
This is because of type-unstable code in sumofsins1 where the type of r needs to be checked for every iteration.
