How to call Matlab transfer function from Python using Matlab engine?

Question

Xin Qi Liu 2021-12-25

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1617440-how-to-call-matlab-transfer-function-from-python-using-matlab-engine

回答： Kojiro Saito 2022-1-18

I am trying to use Matlab in Python and was creating a simple transfer function defined as such using the following code:

% Basic imports
from matlab import engine
import matplotlib.pyplot as plt
import numpy as np
import skfuzzy
% Starting Engine
eng = engine.start_matlab()
% Defining my transfer function
num = [27]
den = [1, 1]
sys1 = eng.tf(num, den)

Running this line on Matlab worked just fine:

num = [27]
den = [1, 1]
sys1 = eng.tf(num, den)

But on Python, I receive this error:

---------------------------------------------------------------------------
MatlabExecutionError                      Traceback (most recent call last)
<ipython-input-24-6f760c3f7a44> in <module>
      1 num = [27]
      2 den = [1, 1]
----> 3 sys1 = eng.tf(num, den)
C:\Anaconda\lib\site-packages\matlab\engine\matlabengine.py in __call__(self, *args, **kwargs)
     68             return FutureResult(self._engine(), future, nargs, _stdout, _stderr, feval=True)
     69         else:
---> 70             return FutureResult(self._engine(), future, nargs, _stdout,
     71                                 _stderr, feval=True).result()
     72 
C:\Anaconda\lib\site-packages\matlab\engine\futureresult.py in result(self, timeout)
     65                 raise TypeError(pythonengine.getMessage('TimeoutCannotBeNegative'))
     66 
---> 67         return self.__future.result(timeout)
     68 
     69     def cancel(self):
C:\Anaconda\lib\site-packages\matlab\engine\fevalfuture.py in result(self, timeout)
     80                 raise TimeoutError(pythonengine.getMessage('MatlabFunctionTimeout'))
     81 
---> 82             self._result = pythonengine.getFEvalResult(self._future,self._nargout, None, out=self._out, err=self._err)
     83             self._retrieved = True
     84             return self._result
MatlabExecutionError: 
  File C:\Program Files\MATLAB\R2021b\toolbox\control\ctrlmodels\@tf\tf.m, line 370, in tf.tf
The values of the "Numerator" and "Denominator" properties must be arrays of compatible sizes.

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VBBV 2021-12-26

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Answer 1

Kojiro Saito 2022-1-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1617440-how-to-call-matlab-transfer-function-from-python-using-matlab-engine#answer_876565

在 MATLAB Online 中打开

As this document describes, Python's list will be converted to cell array in MATLAB Engine.

Simple way is to convert the list to matlab.double type.

import matlab.engine
# Starting Engine
eng = engine.start_matlab()
# Defining my transfer function
num = matlab.double([27])
den = matlab.double([1, 1])
sys1 = eng.tf(num, den)