[julia-users] Equivalent of Matlab zpk()?

[Joe Tusek]

I've been translating some Matlab code for calculating a 
spectral optimisation function that uses Matlab's zpk() function and I 
can't find an equivalent in Julia packages. The DSP.jl looks like its a 
start on a well appointed package but is a bit thin at this stage. Is there 
anything out there than can be substituted for zpk()?  Control.jl looks 
like a start also but is not published.