RSB(3F)

NAME
     RSB, SRSB   -  EISPACK routine.  This subroutine calls the recommended
     sequence of subroutines from the eigensystem subroutine package (EISPACK)
     to find the eigenvalues and eigenvectors (if desired) of a REAL SYMMETRIC
     BAND matrix.


SYNOPSYS
          subroutine  rsb(nm, n, mb, a, w, matz, z, fv1, fv2, ierr)
          integer           nm, n, mb, matz, ierr
          double precision a(nm,mb),w(n),z(nm,n),fv1(n),fv2(n)

          subroutine srsb(nm, n, mb, a, w, matz, z, fv1, fv2, ierr)
          integer           nm, n, mb, matz, ierr
          real             a(nm,mb),w(n),z(nm,n),fv1(n),fv2(n)



DESCRIPTION
     On Input
     NM must be set to the row dimension of the two-dimensional array
     parameters as declared in the calling program dimension statement.

     N is the order of the matrix  A.

     MB is the half band width of the matrix, defined as the number of
     adjacent diagonals, including the principal diagonal, required to specify
     the non-zero portion of the lower triangle of the matrix.

     A contains the lower triangle of the real symmetric band matrix.  Its
     lowest subdiagonal is stored in the last  N+1-MB  positions of the first
     column, its next subdiagonal in the last  N+2-MB  positions of the second
     column, further subdiagonals similarly, and finally its principal
     diagonal in the  N  positions of the last column.  Contents of storages
     not part of the matrix are arbitrary.

     MATZ is an integer variable set equal to zero if only eigenvalues are
     desired.  Otherwise it is set to any non-zero integer for both
     eigenvalues and eigenvectors.  On Output

     W contains the eigenvalues in ascending order.

     Z contains the eigenvectors if MATZ is not zero.

     IERR is an integer output variable set equal to an error completion code
     described in section 2B of the documentation.  The normal completion code
     is zero.

     FV1 and  FV2  are temporary storage arrays. Questions and comments should
     be directed to B. S. Garbow, APPLIED MATHEMATICS DIVISION, ARGONNE
     NATIONAL LABORATORY