[SciPy-user] signal.lti

Stefan van der Walt stefan at sun.ac.za
Sat Sep 9 02:30:42 CDT 2006

On Fri, Sep 08, 2006 at 07:12:35PM -0600, Travis Oliphant wrote:
> Ryan Krauss wrote:
> >I am having a rough time trying to use the lti portion of
> >scipy.signal.  For starters, I just wanted to generate a step response
> >for an integrator (1/s). 
> >
> It turns out your starting-point is a special-case not handled by the 
> current code (I checked this on old SciPy and it raised errors as 
> well).   The current code is "general-purpose" but does not handle 
> lonely integrators.  Thus, any time your denominator ends in a zero, you 
> will have trouble.  This case needs to be dealt with separately but so 
> far isn't (the error could be more informative of course).  You would be 
> better of trying a simple first-order system as your starting point.

Interestingly, he didn't get the

IndexError: index out of bounds

that I see, but rather

TypeError: array cannot be safely cast to required type

which is what lead me to ask about the 64-bit platform.  Same problem?


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