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widen signature of randn!(::MersenneTwister, ::Array{Float64}) ? #49388

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@bjarthur

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@bjarthur

why should this performance optimization not include all AbstractArrays{Float64}s ? i haven't tested any changes to the Random stdlib, but simply looking at the code i think it should work for AbstractArrays too, like this: randfun!(rng::MersenneTwister, A::AbstractArray{Float64}).

the reason i ask, is that for testing purposes i need to generate the same random numbers with and without physical units using Unitful.jl. to do so, one currently must strip off the units using ustrip, which uses reinterpret, and hence returns a ReinterpretArray, which then dispatches to the non-optimized code, leading to different random numbers.

julia> using Unitful, Random

julia> len=15;

julia> rng = MersenneTwister();

julia> a = zeros(len);

julia> Random.seed!(rng, 1);

julia> randn!(rng, ustrip(a))
15-element Vector{Float64}:
  0.2972879845354616
  0.3823959677906078
 -0.5976344767282311
 -0.01044524463737564
 -0.839026854388764
  0.31111133849833383
  2.2950878238373105
  0.40839583832475224
  0.2290095549097807
 -2.2670863488005306
  0.5299655761667461
  0.43142152642291204
  0.5837082875687786
  0.9632716050381906
  0.45879095505371686

julia> ua = zeros(len) * 1u"s";

julia> Random.seed!(rng, 1);

julia> randn!(rng, ustrip(ua))
15-element reinterpret(Float64, ::Vector{Quantity{Float64, 𝐓, Unitful.FreeUnits{(s,), 𝐓, nothing}}}):
  0.2972879845354616
  0.3823959677906078
 -0.5976344767282311
 -0.01044524463737564
 -0.839026854388764
  0.31111133849833383
  2.2950878238373105
 -2.2670863488005306
  0.5299655761667461
  0.43142152642291204
  0.5837082875687786
  0.9632716050381906
  0.45879095505371686
 -0.5223367574215084
  0.40839583832475224

cc: @rfourquet

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