Problem with equality constraints

[SP]

Hi, Johan

I tried the following simple code to test equality constraint.

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P = sdpvar(4,4,'full')  % define a 4 by 4 matrix

C = [sum(P,2)==1]; % row sum equals to 1

solvesdp( C, norm(P-eye(4),2)) % minimize the 2-norm P - I

PP = double(P)

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Matlab resutls: 

 Result:  infeasibility

 The LMI constraints were found INFEASIBLE

PP =

   NaN   NaN   NaN   NaN

   NaN   NaN   NaN   NaN

   NaN   NaN   NaN   NaN

   NaN   NaN   NaN   NaN

Intuitively, the optimal value P should be identity matrix. If I remove the equality constraint

solvesdp( [], norm(P-eye(4),2)) % minimize the 2-norm P - I

It gives the correct answer, i.e., P = I.

Do I code the equality constraint wrongly? How shall I fix the problem? Thanks in advance. 

[Johan Löfberg]

http://users.isy.liu.se/johanl/yalmip/pmwiki.php?n=Solvers.LMILAB

[SP]

I installed Sedumi, and the problem is resolved. Thanks so much for your help!!