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location  Can Pastilla  
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There is nothing more practical than a good theory.
1d

accepted  Positive solutions of linear systems with a diagonally dominant matrix 
Jan 27 
answered  What's the most efficient way to solve this euclidean projection on nonnegative affine space constraint? 
Jan 14 
revised 
Positive solutions of linear systems with a diagonally dominant matrix
added 163 characters in body 
Jan 14 
asked  Positive solutions of linear systems with a diagonally dominant matrix 
Jan 13 
awarded  Necromancer 
Sep 24 
awarded  Autobiographer 
Aug 28 
answered  Simultaneous maximization of two Generalized Rayleigh Ritz Ratios 
Aug 28 
answered  Semi Definite Relaxation for a Quadratic Feasibility Problem using CVX 
Jun 25 
awarded  Citizen Patrol 
Feb 12 
comment 
Solution Existence of a System of Complex Quadratic Equations
I would like to know the conditions so that there is a solution to the equation system. 
Feb 12 
revised 
Solution Existence of a System of Complex Quadratic Equations
added 11 characters in body 
Feb 11 
comment 
Solution Existence of a System of Complex Quadratic Equations
Q_{ij} are complex hermitian matrices. 
Feb 11 
revised 
Solution Existence of a System of Complex Quadratic Equations
added 85 characters in body 
Feb 11 
asked  Solution Existence of a System of Complex Quadratic Equations 
Sep 11 
comment 
Reference Request (semidefinite relaxation)
Ok, I done it. Thank you. 
Sep 11 
revised 
Reference Request (semidefinite relaxation)
added 121 characters in body 
Sep 10 
asked  Reference Request (semidefinite relaxation) 
May 23 
answered  Estimating a sum 
Dec 16 
comment 
Minimizing ellipsoid over intersection of ellipsoids
Yes, use $\X \approx \lambda_{\text{max}}uu^T$ where $\lambda_{\text{max}}$ is the maximum eigenvalue with u eigenvector. There are other approximations but I barely remenber them... 
Dec 15 
comment 
Minimizing ellipsoid over intersection of ellipsoids
Yes: i) Your problem as it is, is nonconvex ii) Semidefinite programming relaxation can give you an approximate solution of the problem (since you are dropping the rankone constraint). iii) There might be the case where ALWAYS the semidefinite relaxation gives a rankone solution. In that case, the solution to the semidefinite relaxation is the optimal value of your problem. Results about this are derived via studying the dual problem of the semidefinite relaxation. 