_IMTQL1(3F)_IMTQL1(3F)NAME
IMTQL1, SIMTQL1 - EISPACK routine. This subroutine finds the
eigenvalues of a SYMMETRIC TRIDIAGONAL matrix by the implicit QL method.
SYNOPSYS
subroutine imtql1(n, d, e, ierr)
integer n, ierr
double precision d(n), e(n)
subroutine simtql1(n, d, e, ierr)
integer n, ierr
real d(n), e(n)DESCRIPTION
On INPUT
N is the order of the matrix.
D contains the diagonal elements of the input matrix.
E contains the subdiagonal elements of the input matrix in its last N-1
positions. E(1) is arbitrary. On OUTPUT
D contains the eigenvalues in ascending order. If an error exit is made,
the eigenvalues are correct and ordered for indices 1,2,...IERR-1, but
may not be the smallest eigenvalues.
E has been destroyed.
IERR is set to ZERO for normal return, J if the J-th
eigenvalue has not been
determined after 30 iterations. Calls PYTHAG(A,B) for sqrt(A**2 +
B**2). Questions and comments should be directed to B. S. Garbow,
APPLIED MATHEMATICS DIVISION, ARGONNE NATIONAL LABORATORY
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