Skip to content

Can't step a zero degree polynomial #165

Description

@marianomds

When running:

import control as ctrl
G = ctrl.tf([1],[1])
(y, t) = ctrl.step(G)

I get this error (I get the same in python 2.7 and 3.5):

Traceback (most recent call last):
File "./prueba.py", line 10, in
(y, t) = ctrl.step(G)
File "/usr/local/lib/python3.5/dist-packages/control/matlab.py", line 1328, in step
transpose = True, **keywords)
File "/usr/local/lib/python3.5/dist-packages/control/timeresp.py", line 483, in step_response
sys = _get_ss_simo(sys, input, output)
File "/usr/local/lib/python3.5/dist-packages/control/timeresp.py", line 409, in _get_ss_simo
sys_ss = _convertToStateSpace(sys)
File "/usr/local/lib/python3.5/dist-packages/control/statesp.py", line 656, in _convertToStateSpace
ssout = td04ad('R',sys.inputs, sys.outputs, index, den, num,tol=0.0)
File "/usr/local/lib/python3.5/dist-packages/slycot/transform.py", line 423, in td04ad
out = _wrapper.td04ad_r(m,p,index,dcoeff,ucoeff,n,tol,ldwork)
ValueError: failed to create intent(cache|hide)|optional array-- must have defined dimensions but got (1,0,)

Activity

  1. murrayrm commented on Dec 27, 2017

    @murrayrm
    Member

    Confirmed that this is a bug in the latest versions of the code (including several fixes). The time response functions are not set up to handle static systems properly. Marking as an 'enhancement' since this is a somewhat unusual case. Shouldn't be too much trouble to fix. We should also check to make sure that various other functions (eg, Bode and Nyquist plots, root locus, etc) function properly or give an appropriate error message.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Metadata

Metadata

Assignees

No one assigned

    Type

    No type

    Projects

    No projects

      Milestone

      No milestone

      Relationships

      None yet

      Development

      No branches or pull requests

      Issue actions