Re: [python-control-discuss] really weird error for SISO step response

[Ryan K. <kra...@gv...>]

I guess I have to upgrade to OSX 10.14 to get xcode back......

This could take a minute.....

--
Dr. Ryan Krauss
Associate Professor
Product Design and Manufacturing Engineering
Grand Valley State University


On Fri, Aug 30, 2019 at 11:26 AM Ryan Krauss <kra...@gv...> wrote:

> I just ran a pip upgrade for the control module.  I am running 0.8.2.
>
> I just tried upgrading slycot via pip.  pip says I am currently running
> 0.3.0.  I tried to upgrade to 0.3.5 via pip, but I receive error messages
> about gfortran and xcode.  I am kind of surprised that I don't have them
> both working.  I will work on that.
>
> I am getting False for this variable: slycot.__SLYCOT_SETUP__
>
> --
> Dr. Ryan Krauss
> Associate Professor
> Product Design and Manufacturing Engineering
> Grand Valley State University
>
>
> On Fri, Aug 30, 2019 at 2:16 AM Murray, Richard M. <mu...@cd...>
> wrote:
>
>> Which version of python-control and slycot?  I just ran against the
>> latest master and slycot 0.3.4 and it didn’t generate an error.
>>
>> -richard
>>
>> > On 29 Aug 2019, at 11:04 , Ryan Krauss <kra...@gv...> wrote:
>> >
>> > I am trying to do a super basic step response for a first order TF and
>> am getting an error I have never seen before.  The notebook is attached,
>> but here is the code and the error message:
>> >
>> > %matplotlib inline
>> > import matplotlib.pyplot as plt
>> > import numpy as np
>> > import control
>> > from numpy import sin, cos, tan, pi
>> > from control import TransferFunction as TF
>> >
>> > p = 30
>> >
>> > G = control.TransferFunction(p,[1,p])
>> > G
>> >
>> > control.step_response(G)
>> >
>> >
>> ---------------------------------------------------------------------------
>> > ValueError
>> >                                 Traceback (most recent call last)
>> >
>> > <ipython-input-7-7235fbf92fdd> in <module>()
>> > ----> 1 control.step_response(G)
>> >
>> >
>> >
>> > /usr/local/lib/python3.6/site-packages/control/timeresp.py in
>> step_response(sys, T, X0, input, output, transpose, return_x)
>> >     450     >>> T, yout = step_response(sys, T, X0)
>> >     451
>> >      """
>> >
>> > --> 452     sys = _get_ss_simo(sys, input, output)
>> >     453     if T is None:
>> >     454         if isctime(sys):
>> >
>> >
>> >
>> > /usr/local/lib/python3.6/site-packages/control/timeresp.py in
>> _get_ss_simo(sys, input, output)
>> >     378     If input is not specified, select first input and
>> >  issue warning
>> >
>> >     379
>> >      """
>> >
>> > --> 380     sys_ss = _convertToStateSpace(sys)
>> >     381     if sys_ss.issiso():
>> >     382         return
>> >  sys_ss
>> >
>> >
>> > /usr/local/lib/python3.6/site-packages/control/statesp.py in
>> _convertToStateSpace(sys, **kw)
>> >     895             # transfer function to state space conversion now
>> should work!
>> >     896
>> >              ssout = td04ad('C', sys.inputs, sys.outputs,
>> >
>> > --> 897
>> >                             denorder, den, num, tol=0)
>> >
>> >     898
>> >
>> >
>> >     899             states = ssout[0]
>> >
>> >
>> >
>> > /usr/local/lib/python3.6/site-packages/slycot/transform.py in
>> td04ad(rowcol, m, p, index, dcoeff, ucoeff, tol, ldwork)
>> >     446         e = ValueError(error_text)
>> >     447         e.info = out[-1]
>> > --> 448         raise
>> >  e
>> >
>> >     449     if out[-1] > 0:
>> >     450         error_text = "The leading coefficient of a denominator
>> polynomial is nearly zero; calculations would overflow; no state-space
>> representation was calculated.
>> ABS(DCOEFF("+str(out[-1])+",1))="+str(abs(dcoeff(out[-1],1)))+" is too
>> small."
>> >
>> >
>> >
>> > ValueError: The following argument had an illegal value: dcoeff
>> >
>> > --
>> > Dr. Ryan Krauss
>> > Associate Professor
>> > Product Design and Manufacturing Engineering
>> > Grand Valley State University
>> > <illegeal_dcoeff.ipynb>_______________________________________________
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>>
>>
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