> I recently poked around a bit with the @code_warntype macro in my code and
> quickly realized that a lot of my variables were assigned "Any" at compile
> time. I tried to find the reason for it and got down to the eig function:
>
> julia> @code_warntype eig(rand(Float64, 5,5))
> Variables:
> A::Array{Float64,2}
> args::Tuple{}
>
> Body:
> begin $(Expr(:line, 66, symbol("linalg/eigen.jl"), symbol("")))
> GenSym(8) = (top(ccall))(:jl_alloc_array_1d,$(Expr(:call1,
> :(top(apply_type)), :Array, Any, 1)),$(Expr(:call1, :(top(svec)), :Any,
> :Int)),Array{Any,1},0,0,0)::Array{Any,1}
> GenSym(9) = GenSym(8)
> return __eig#179__(GenSym(9),A::Array{Float64,2})::Tuple{Any,Any}
> end::Tuple{Any,Any}
>
>
> Is there a reason this returns Tuple{Any, Any} instead of Tuple{Complex128,
> Complex128} as you might expect? As far as I understand it this causes
> everything touched by the eig function to become type unstable.
The reason is the method getindex(A::Union{Eigen,GeneralizedEigen},
d::Symbol) near the top of base/linalg/eigen.jl which is not type
stable. This is then used in eig. Have a look at it with
@edit eig(rand(Float64, 5,5))
I suspect this is a bug, you should file a report. In the meantime you
can monkey patch by adding this to your code:
function Base.eig(A::Union{Number, AbstractMatrix}, args...; kwargs...)
F = eigfact(A, args...; kwargs...)
F.values, F.vectors
end
