The matrix is in the form of Ax=SBx where S is the eigen value. Both A and B are large sparse matrices. The number of elements are 4266*4266. I am using EISPACK for obtaining the eigen values but getting NAN or infinity as a solution. I have checked both A and B matrices and they were correct. Is it possible that my pc is unable to do such big calculations? Is parallel computing required for such large sparse matrices?