the dual function in yalmip

[Xiaoxi Wang]

hi

i cannot extract the dual variable by using the dual function

I use the sample code from our website  http://users.isy.liu.se/johanl/yalmip/pmwiki.php?n=Commands.Dual
A = [-1 2;-3 -4];

P = sdpvar(2,2);
F = [P >= 0, A'*P+P*A <= 0, trace(P) == 1];
solvesdp(F);
Z2 = dual(F(2));

but the result i get NaN, It is not a number

i install the yalmip as what the yalmip wiki said

So can you show me the result of this sample code

Or is there are other toolbox i need to install

[Johan Löfberg]

This happens if

1. The solver has crashed or
2. you don't have any solver installed or
3. you only have LMILAB installed (/does not compute duals)

Show us the solver print-out, and the diagnostic returned from solvesdp