Re: [python-control-discuss] call method

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

FYI, I made this change in my local checkout code and ran a simple test and
it is working:

In [8]: test = control.TransferFunction(1,[1,3])

In [9]: s1 = -1+2.0j

In [10]: test(s1)
Out[10]: (0.25-0.25j)

In [11]: 1.0/(s1+3)
Out[11]: (0.25-0.25j)

Nothing too fancy, but solves my issue.


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


On Thu, Jun 6, 2013 at 1:47 PM, Ryan Krauss <rk...@si...> wrote:

> 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
>