[Copilot]

The transfer module listed sos2ss, sos2tf, and sos2zp as planned but unimplemented. This adds all three.

New functions

• sos2tf(sos) — wraps scipy.signal.sos2tf; converts SOS array → transfer function (b, a)
• sos2zp(sos) — wraps scipy.signal.sos2zpk; converts SOS array → zeros/poles/gain (z, p, k)
• sos2ss(sos) — converts SOS array → state-space (A, B, C, D) by chaining sos2tf → scipy.signal.tf2ss

import scipy.signal
from spectrum.transfer import sos2ss, sos2tf, sos2zp

sos = scipy.signal.butter(4, 0.2, output='sos')

b, a   = sos2tf(sos)          # transfer function
z, p, k = sos2zp(sos)         # zero-pole-gain
A, B, C, D = sos2ss(sos)      # state-space

All three are exported via __all__.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>sos2ss implementation</issue_title>
<issue_description>Hello, is there any plan to implement sos2ss function in python?</issue_description>

Comments on the Issue (you are @copilot in this section)

@cokelaer @iPsych not now but if you have a prototype, or are willing to add a PR, I'll be more than happy to incorporate it in the package with your contributions of course

• Fixes sos2ss implementation #74

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[coveralls]

coverage: 97.017% (+0.01%) from 97.006%
when pulling 5eb290d on copilot/implement-sos2ss-function
into 080e5aa on master.

[coveralls]

coverage: 97.017% (+0.01%) from 97.006%
when pulling 5eb290d on copilot/implement-sos2ss-function
into 080e5aa on master.