How to Display CVX Decision Variables after cvx_end

1

Hi there,

I have a presumably silly question. New to CVX, read the User’s guide, but unfortunately, I just can’t find, how the decision variable can be displayed. I can see the optimized solution, ie the objective function value(optval_cvx). But, the values of the decision variables are just not visible. If I try displaying the decision variable ‘x(n)’ after cvx_end using matlab code,it just says ‘undefined variable or function’.

Edit:
The problem was that, I was building a function, within which cvx was called. Since the workspace displays only values returned by the function, I was unable to see the decision variables. The function containing cvx script, returned only the optimal solution.

2

After CVX completes, the decision variables will contain the optimal values. If you declared variable x(n), then x will be a vector of optimal values. x(n) will be the nth element of x.

Here is a simple example:

n = 2;
cvx_begin
variable x(n)
minimize(norm(x))
x >= 1
cvx_end   
<edited out solution information>
Status: Solved
Optimal value cvx_optval): +1.41421
        
disp(x)
1.000000001825649
1.000000001825649

If you are still having trouble, please show your complete code.

3

Hi Mark,

Thank you very much for answering this question. I think, I didn’t specify the problem correctly. (I’m new to Matlab as well). See Edit.