[SciPy-user] signal.lti

Nils Wagner nwagner at iam.uni-stuttgart.de
Tue Sep 12 04:17:47 CDT 2006


Lars Friedrich wrote:
> Hello,
>
>   
>> Ryan Krauss wrote:
>>
>>     
>>> I thought about this over the weekend.  I was wrong about the matrices
>>> not being correct.  The A matrix really is just 0.  So, passing in the
>>> numerator and denominator polynomials does correctly create a system,
>>> you just can't take its step response.
>>>       
>
> shouldn't signal.lsim2 be able to handle such systems? I tried the
> following:
>
> #*************** start shell session
> from scipy import signal
> from numpy import *
>
> sys1=signal.lti((1),(1,0))
>
> signal.lsim2(sys1, ones(10), arange(10))
>
> Traceback (most recent call last):
>   File "<input>", line 1, in ?
>   File "/usr/lib/python2.4/site-packages/scipy/signal/ltisys.py", line
> 333, in lsim2
>     ufunc = interpolate.linear_1d(T, U, axis=0, bounds_error=0,
> fill_value=0)
> AttributeError: 'module' object has no attribute 'linear_1d'
> #***************** end shell session
>
> What about this error? I get the same errror with
> sys=signal.lti((1),(1,1)).
>
> Thanks
> Lars
>
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>   
BTW, an "entry" for lsim2 is missing

help (signal) yields ...

     Linear Systems:

        lti -- linear time invariant system object.
        lsim -- continuous-time simulation of output to linear system.
        impulse -- impulse response of linear, time-invariant (LTI) system.
        step -- step response of continous-time LTI system.

Nils



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