`similarity_transform(sys, T)` throws an error when transformation matrix `T` is complex

[tfoliva]

Using Version 0.9.2.

Trying to perform a similarity transformation with a complex matrix returns

ERROR: InexactError: Float64(-5.159983634948731 - 4116.475358187984im)
Stacktrace:
 [1] Real at ./complex.jl:37 [inlined]
 [2] convert at ./number.jl:7 [inlined]
 [3] setindex! at ./array.jl:847 [inlined]
 [4] _unsafe_copyto!(::Array{Float64,2}, ::Int64, ::Array{Complex{Float64},2}, ::Int64, ::Int64) at ./array.jl:257
 [5] unsafe_copyto! at ./array.jl:311 [inlined]
 [6] _copyto_impl! at ./array.jl:335 [inlined]
 [7] copyto! at ./array.jl:321 [inlined]
 [8] copyto! at ./array.jl:347 [inlined]
 [9] copyto_axcheck! at ./abstractarray.jl:946 [inlined]
 [10] Array{Float64,2}(::Array{Complex{Float64},2}) at ./array.jl:562
 [11] convert at ./array.jl:554 [inlined]

I needed to convert a system to modal canonical form, so I implemented a similar function which performs the eigendecomposition, (similar to MATLAB's prescale I guess). I can make a pull request. Furthermore, are there plans to implement this system transformations (controlable canonical form, observable canonical form, modal canonical form)?

[baggepinnen]

Hey and thanks for the issue. Feel free to make such PR, that'd be great. The implementation effort going into this package is mostly driven by need, so unless someone needs it and implements it, it's unfortunately unlikely to happen.