Re: [python-control-discuss] problem with TransferFuntion.__call__ with 2D input

[Richard M. <mu...@cd...>]

Thanks, Ryan.  I'll look through this and try to put the patch into the repository soon (hopefully this weekend).

-richard

On 28 Aug 2013, at 9:33 , Ryan Krauss <rk...@si...> wrote:

> I left the original code intact for cases when s is a 1D array, but that isn't really necessary.  My second patch eliminates this unnecessary case in the if statement:
> 
>     def horner(self, s):
>         """Evaluate the systems's transfer function for a complex variable
>         
>         Returns a matrix of values evaluated at complex variable s.
>         """
> 
>         # Preallocate the output.
>         if getattr(s, '__iter__', False):
>             dim = [self.outputs, self.inputs]
>             dim.extend(shape(s))
>             out = empty(dim, dtype=complex)
>         else:
>             out = empty((self.outputs, self.inputs), dtype=complex)
> 
>         for i in range(self.outputs):
>             for j in range(self.inputs):
>                 out[i][j] = (polyval(self.num[i][j], s) / 
>                     polyval(self.den[i][j], s))
> 
>         return out
> 
> A second patch is attached.
> 
> 
> --
> Ryan Krauss, Ph.D.
> Associate Professor
> Mechanical Engineering
> Southern Illinois University Edwardsville
> 
> 
> On Wed, Aug 28, 2013 at 11:28 AM, Ryan Krauss <rk...@si...> wrote:
> This might be slightly hackish, but I think it solves the problem.  The core issue is the size of the out matrix created at the beginning of the horner method.  out needs to be 4D is s is a 2D array.  I think this works for any dimension of s.
> 
>     def horner(self, s):
>         """Evaluate the systems's transfer function for a complex variable
>         
>         Returns a matrix of values evaluated at complex variable s.
>         """
> 
>         # Preallocate the output.
>         if getattr(s, '__iter__', False):
>             if len(shape(s)) == 1:
>                 out = empty((self.outputs, self.inputs, len(s)), dtype=complex)
>             else:
>                 dim = [self.outputs, self.inputs]
>                 dim.extend(shape(s))
>                 out = empty(dim, dtype=complex)
>         else:
>             out = empty((self.outputs, self.inputs), dtype=complex)
> 
>         for i in range(self.outputs):
>             for j in range(self.inputs):
>                 out[i][j] = (polyval(self.num[i][j], s) / 
>                     polyval(self.den[i][j], s))
> 
>         return out
> 
> I am attaching a patch of my hack.
> 
> 
> 
> --
> Ryan Krauss, Ph.D.
> Associate Professor
> Mechanical Engineering
> Southern Illinois University Edwardsville
> 
> 
> On Wed, Aug 28, 2013 at 11:06 AM, Ryan Krauss <rk...@si...> wrote:
> I need to calculate 3D bode plots (contour plots) for my work.  I am getting this error:
> 
> /usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/control-0.6d-py2.7.egg/control/xferfcn.pyc in __call__(self, s)
>     245         else:
>     246             # SISO transfer function, return a scalar
> --> 247             return self.horner(s)[0][0]
>     248 
>     249     def _truncatecoeff(self):
> 
> /usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/control-0.6d-py2.7.egg/control/xferfcn.pyc in horner(self, s)
>     560             for j in range(self.inputs):
>     561                 out[i][j] = (polyval(self.num[i][j], s) / 
> --> 562                     polyval(self.den[i][j], s))
>     563 
>     564         return out
> 
> ValueError: could not broadcast input array from shape (2,2) into shape (2)
> 
> 
> Here is code that recreates the problem:
> 
> import control
> test = control.TransferFunction(1,[1,1])
> s_mat = array([[2j*pi, 3j*pi],[-0.1+2j*pi, -0.1+3j*pi]])
> 
> 
> 
> --
> Ryan Krauss, Ph.D.
> Associate Professor
> Mechanical Engineering
> Southern Illinois University Edwardsville
> 
> 
> <krauss_horner_patch_2.diff>------------------------------------------------------------------------------
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