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From: Ryan K. <kra...@gv...> - 2019-08-30 01:28:36
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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
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