Using 'eigs' to find eigen values for singular sparse matrix

Hi all,

   I am working on a problem which deals with two huge matrices (with size greater than 5000 x 5000) . One matrix is full (say Matrix A) and symmetric and the second matrix is sparse and singular (say Matrix B)....

I was trying to find eigen values and vectors using the inbuilt Matlab function 'eig(A,B)', but ended up in having memory issues... so I tried using 'eigs(A.B)' function by defining the second matrix (B) as a sparse matrix.

But 'eigs()' couldn't find the eigen values since matrix B is singular... Is there any way to find use 'eigs()' with singular matrices ??