_RSB(3F)_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
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