[python-control-discuss] call method

[Ryan K. <rk...@si...>]

I would like to submit some minor patches over the course of the summer to
help me completely get rid of my old controls module and switch over to
python-control for everything.  My most immediate need is for a __call__
method.  This method might not make any sense for a state-space system, but
for certain aspects of my modeling work, I need to evaluate transfer
functions at certain numerical values of s.

I would propose something like this:

def __call__(self, s):
    """Evaluate a transfer function at s."""
    N_poly = poly1d(squeeze(self.num))
    D_poly = poly1d(squeeze(self.den))
    return N_poly(s)/D_poly(s)


It could also include a check that self is SISO and possibly throw an
exception if it is not (pretty sure that poly1d will throw one if we pass
in a vector of coefficients that isn't 1d).

Would this be welcome?  Is there anything I should tweak?

Thanks,

Ryan

--
Ryan Krauss, Ph.D.
Associate Professor
Mechanical Engineering
Southern Illinois University Edwardsville