How can I use the eig function

# How can I use the eig function in CVX

**Mark_L_Stone**(Mark L. Stone) #2

You can use lambda_min, lambda_max, lambda_sum_largest, and lambda_sum_smallest.

**xcc**(xucheng) #3

I am sorry that my English is poor and I start to use CVX recently.I did not get your point.The problem is as following:

**xcc**(xucheng) #4

Is this problem convex?And can I use the A==-hermitian_semidefinite(N) denotes the constraint A is negative semidefinite?

**Mark_L_Stone**(Mark L. Stone) #5

I believe that will work. Or use

`-A == hermitian_semidefinite(N)`

Note that as I guessed might be the case in your other question, you want to constrain a matrix to be negative semidefinite. That is not the same as constraining a matrix to not be positive semidefinite. They are not equivalent because the latter includes the possibility of the matrix being indefinite.