Use LOBPCG with Epetra, with shifted eigenvalue problem.

Use LOBPCG with Epetra, with shifted eigenvalue problemThis example computes the eigenvalues of largest magnitude of the discretized 2-D Laplacian operator, using Anasazi's implementation of the LOBPCG method. This problem constructs a shifted eigenproblem that targets the smallest eigenvalues around a certain value (sigma). This operator is discretized using linear finite elements and constructed as an Epetra matrix, then passed shifted using EpetraExt utilities.