Recent content by Jimmy and Bimmy

  1. J

    Graduate How do I supply arpack drivers with all starting vectors?

    I am using arpack (the dsdrv1 driver) to iteratively solve the eigenvalue problem Ax = λx I am interested in the first m eigenvectors, and I have very good initial approximations for these vectors, so I would like to use my m starting vectors as an initial guess. However...
  2. J

    Graduate Efficiently Computing Eigenvalues of a Sparse Banded Matrix

    Thanks for the reply. I have been using dsyev from the lapack routine (which is for symmetric matrices). I switched to dsbev (which is for symmetric band matrices), but didn't see much improvement. This is because, even though I only have 5 bands (diagonal + 2 upper + 2 lower), the outer 2...
  3. J

    Graduate Efficiently Computing Eigenvalues of a Sparse Banded Matrix

    I have a Hamiltonian represented by a penta-diagonal matrix The first bands are directly adjascent to the diagonals. The other two bands are N places above and below the diagonal. Can anyone recommend an efficient algorithm or routine for finding the eigenvalues and eigenvectors?