boundary conditions

[Manav Bhatia]

Hi,

   I am trying to solve an eigenproblem. I would like to apply  
boundary conditions by removing the rows and columns associated with  
these dofs (as opposed to retaining/zeroing them and setting the  
diagonal elements to unit values).

   Is there a way for me to tell the matrix data structure which dofs  
to ignore during the matrix operations? Or should I create a separate  
matrix by extracting the unconstrained dofs from the global matrix?

   I would appreciate any inputs.

Thanks,
Manav