subroutine rst(nm,n,w,e,matz,z,ierr)
c
integer i,j,n,nm,ierr,matz
real w(n),e(n),z(nm,n)
c
c this subroutine calls the recommended sequence of
c subroutines from the eigensystem subroutine package (eispack)
c to find the eigenvalues and eigenvectors (if desired)
c of a real symmetric tridiagonal matrix.
c
c on input
c
c nm must be set to the row dimension of the two-dimensional
c array parameters as declared in the calling program
c dimension statement.
c
c n is the order of the matrix.
c
c w contains the diagonal elements of the real
c symmetric tridiagonal matrix.
c
c e contains the subdiagonal elements of the matrix in
c its last n-1 positions. e(1) is arbitrary.
c
c matz is an integer variable set equal to zero if
c only eigenvalues are desired. otherwise it is set to
c any non-zero integer for both eigenvalues and eigenvectors.
c
c on output
c
c w contains the eigenvalues in ascending order.
c
c z contains the eigenvectors if matz is not zero.
c
c ierr is an integer output variable set equal to an error
c completion code described in the documentation for imtql1
c and imtql2. the normal completion code is zero.
c
c questions and comments should be directed to burton s. garbow,
c mathematics and computer science div, argonne national laboratory
c
c this version dated august 1983.
c
c ------------------------------------------------------------------
c
if (n .le. nm) go to 10
ierr = 10 * n
go to 50
c
10 if (matz .ne. 0) go to 20
c .......... find eigenvalues only ..........
call imtql1(n,w,e,ierr)
go to 50
c .......... find both eigenvalues and eigenvectors ..........
20 do 40 i = 1, n
c
do 30 j = 1, n
z(j,i) = 0.0e0
30 continue
c
z(i,i) = 1.0e0
40 continue
c
call imtql2(nm,n,w,e,z,ierr)
50 return
end