MATLAB Answers


How to create matrices of Symbolic Variables in an earlier version of Symbolic toolbox

Asked by Hari
on 18 Jun 2013


Is there any way in which a command with similar functionality as X = sym('x',[2*N,1]); can be worked with an earlier version of Matlab where such commands are not supported..any answer in the right direction will be appreciated.

I currently work on an optimization problem of a throughput model (in commodities). The large number of related variables necessitates me to use symbolic toolbox to create matrices (or arrays) of symbolic vars..Unfortunately, the old version of Matlab is not supporting the command.




3 Answers

Answer by Alan Weiss
on 18 Jun 2013

This might not be as slick as the other answers, but it is in the documentation, and is easy to generalize.

Alan Weiss

MATLAB mathematical toolbox documentation

  1 Comment

Answer by Azzi Abdelmalek
on 18 Jun 2013
Edited by Azzi Abdelmalek
on 18 Jun 2013
evalin('base',['y=sym([x1' sprintf(' ,x%d ',2:N) '])'])


Answer by Andrei Bobrov
on 18 Jun 2013
Edited by Andrei Bobrov
on 18 Jun 2013

2D symbolic array with size [7 x 5]:

m = 7; n = 5;
[ii,jj] = ndgrid(1:n,1:m);
v = sprintf('x%d%d,',[ii(:),jj(:)]');
X = reshape(sym(['[',v(1:end-1),']']),m,[]);

ADD after Alan Weiss's answer

m = 7; n = 5;
[ii,jj] = ndgrid(1:m,1:n);
s = arrayfun(@(x,y)sprintf('x%d_%d',x,y),ii,jj,'un',0);
X = sym(s);


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