[julia-users] Type for eigs result

[James Fairbanks]

We have Base.LinAlg.eig return a tuple of (values,vectors) and 
Base.LinAlg.eigfact returns a type for the result Base.LinAlg.Eigen. But 
Base.LinAlg.eigs returns a tuple would it be worth having a variant of eigs 
that returns a type such as EigsResult?

@doc """a type for the output of eigs


   "eigs" returns the "nev" requested eigenvalues in "d", the
   corresponding Ritz vectors "v" (only if "ritzvec=true"), the
   number of converged eigenvalues "nconv", the number of iterations
   "niter" and the number of matrix vector multiplications
   "nmult", as well as the final residual vector "resid".


   """ ->
type EigsResult{T, R}
 values::Array{T,1}
 vectors::Array{T,2}
 nconv::Int64
 niter::Int64
 nmult::Int64
 resid::Array{R,1}
end


function EigsResult(A; args...)
 @show args
 tupl = eigs(A; args...)
 T = eltype(tupl[1])
 R = eltype(tupl[end])
 EigsResult{T,R}(tupl...)
end

Any function that depends only on the eigenvalues and eigenvectors can take 
either an Eigen or an EigsResult because they have the same field names.

James Fairbanks