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

### Hari (view profile)

on 18 Jun 2013

Hi,

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.

thanks,

Hari

## Products

### Alan Weiss (view profile)

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

Andrei Bobrov

on 18 Jun 2013

+1

### Azzi Abdelmalek (view profile)

on 18 Jun 2013
Edited by Azzi Abdelmalek

### Azzi Abdelmalek (view profile)

on 18 Jun 2013

```N=10;
evalin('base',['y=sym([x1' sprintf(' ,x%d ',2:N) '])'])
```

### Andrei Bobrov (view profile)

on 18 Jun 2013
Edited by Andrei Bobrov

### Andrei Bobrov (view profile)

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,[]);
```

```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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