expm is allocating

[nlw0]

It seems this line from the exp() method

StaticArrays.jl/src/expm.jl

Line 71 in 786b6f0

nA = maximum(sum(abs.(A); dims=Val(1))) # marginally more performant than norm(A, 1)

is causing a couple of allocations, what I imagine is not something desirable. Just using opnorm(A,1) prevents it.

I am not sure how to go about making a PR, should I go for a non-allocating version of this, or just move back to opnorm?

[nlw0]

#579

[c42f]

The underlying problem here seems to be that sum(A; dims=Val(1)) is allocating:

julia> A = @SArray rand(4,4);

julia> @btime sum($A; dims=Val(1))
  28.764 ns (2 allocations: 192 bytes)
1×4 SArray{Tuple{1,4},Float64,2,4} with indices SOneTo(1)×SOneTo(4):
 1.09627  1.93056  1.62516  2.25825

[c42f]

Ultimately root cause may be a dup of #540 and #541

[mateuszbaran]

It's fixed on master (most likely a duplicate of #540).