Limit of nested parentheses in MATLAB

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Tiasa Ghosh 2018-8-22

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https://ww2.mathworks.cn/matlabcentral/answers/415774-limit-of-nested-parentheses-in-matlab

评论： Tiasa Ghosh 2018-8-22

Hello all, I just wanted to know the limit of nested brackets and parentheses in MATLAB. I have some equations with more than 20 brackets and parentheses nesting. Initially it was around 60 and after reading the question in this link, https://de.mathworks.com/matlabcentral/answers/291976-avoid-depth-limit-for-nested-parenthesis-and-brackets, I reduced it to 30 parentheses but still I still get the error Parentheses, brackets, and braces are nested too deeply.

So does anybody know the actual limit of nesting?

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Tiasa Ghosh 2018-8-22

在 MATLAB Online 中打开

I have the equation as a string as:

str={'M(1,7)==((((((((((((((((((((((((((((((mRf(1,1)*phiMatrix(1,1))+(mRf(1,2)*phiMatrix(2,1)))+(mRf(1,3)*phiMatrix(3,1)))+(mRf(1,4)*phiMatrix(4,1)))+(mRf(1,5)*phiMatrix(5,1)))+(mRf(1,6)*phiMatrix(6,1)))+(mRf(1,7)*phiMatrix(7,1)))+(mRf(1,8)*phiMatrix(8,1)))+(mRf(1,9)*phiMatrix(9,1)))+(mRf(1,10)*phiMatrix(10,1)))+(mRf(1,11)*phiMatrix(11,1)))+(mRf(1,12)*phiMatrix(12,1)))+(mRf(1,13)*phiMatrix(13,1)))+(mRf(1,14)*phiMatrix(14,1)))+(mRf(1,15)*phiMatrix(15,1)))+(mRf(1,16)*phiMatrix(16,1)))+(mRf(1,17)*phiMatrix(17,1)))+(mRf(1,18)*phiMatrix(18,1)))+(mRf(1,19)*phiMatrix(19,1)))+(mRf(1,20)*phiMatrix(20,1)))+(mRf(1,21)*phiMatrix(21,1)))+(mRf(1,22)*phiMatrix(22,1)))+(mRf(1,23)*phiMatrix(23,1)))+(mRf(1,24)*phiMatrix(24,1)))+(mRf(1,25)*phiMatrix(25,1)))+(mRf(1,26)*phiMatrix(26,1)))+(mRf(1,27)*phiMatrix(27,1)))+(mRf(1,28)*phiMatrix(28,1)))+(mRf(1,29)*phiMatrix(29,1)))+(mRf(1,30)*phiMatrix(30,1)))'};

where M(1x7), mRf(1x30) and phiMatrix(30x1) are symbolic matrices. And I am using

SymEquations{1,1} = str2sym(str{1});

to convert it to symbolic equation in SymEquations.

Rik 2018-8-22

I'm sorry, I don't have the symbolic toolbox, so I can't test it for you. But I still don't see how you can't use partial equations to generate this.

Also, where does the error originate? Is it Matlab itself that's complaining, or is the deep nesting only a problem for the symbolic toolbox? (we might be able to get a better idea if you post all the red text and/or the result of [errmsg, msgid] = lasterr)

Tiasa Ghosh 2018-8-22

在 MATLAB Online 中打开

The error shows up like this: errmsg =

    'Error using str2sym (line 83)
     Unable to convert string to symbolic expression:
     L 1 (C 158): MDEEP: Parentheses, brackets, and braces are nested too deeply.'
msgid =
      'symbolic:str2sym:UnableToConvert'
    Error using str2sym (line 83)
      Unable to convert string to symbolic expression:
      L 1 (C 116): MDEEP: Parentheses, brackets, and braces are nested too deeply.

I am integrating a wind turbine model from Modelica with a MATLAB toolbox for my purpose and the equations are generated from matrix multiplication for wind turbine model in Modelica. So in Modelica actually what it does is define two matrices with the dimensions and when the model is simulated , the arithmetical operations are done to output the equations. So the equations are not hardwired into the model but are generated while the model is being simulated by Modelica.

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Limit of nested parentheses in MATLAB

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Limit of nested parentheses in MATLAB

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