_RT(3F)_RT(3F)NAME
RT, SRT - 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 special REAL
TRIDIAGONAL matrix.
SYNOPSYS
subroutine rt(nm, n, a, w, matz, z, fv1, ierr)
integer nm, n, matz, ierr
double precision a(nm,3), w(n), z(nm n), fv1(n)
subroutine srt(nm, n, a, w, matz, z, fv1, ierr)
integer nm, n, matz, ierr
real a(nm,3), w(n), z(nm n), fv1(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.
A contains the special real tridiagonal matrix in its first three
columns. The subdiagonal elements are stored in the last N-1 positions
of the first column, the diagonal elements in the second column, and the
superdiagonal elements in the first N-1 positions of the third column.
elements A(1,1) and A(N,3) 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 is a temporary storage array. Questions and comments should be
directed to B. S. Garbow, APPLIED MATHEMATICS DIVISION, ARGONNE NATIONAL
LABORATORY
Page 1
