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Can't step a zero degree polynomial #165
Description
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
murrayrm commentedon Dec 27, 2017
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.