TEVLC(3)

SYNOPSIS
SUBROUTINE TEVLC (N, D, E2, IERR)

NAME
tevlc - Subsidiary to CBLKTR

LIBRARY
SLATEC

TYPE
SINGLE PRECISION (TEVLC-S)

AUTHOR
(UNKNOWN)

DESCRIPTION
This subroutine finds the eigenvalues of a symmetric tridiagonal matrix by the rational QL method. On Input- N is the order of the matrix, D contains the diagonal elements of the input matrix, E2 contains the subdiagonal elements of the input matrix in its last N-1 positions. E2(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, E2 has been destroyed, IERR is set to ZERO for normal return, J if the J-th eigenvalue has not been determined after 30 iterations.

SEE ALSO
CBLKTR

REFERENCES
C. H. Reinsch, Eigenvalues of a real, symmetric, tri- diagonal matrix, Algorithm 464, Communications of the ACM 16, 11 (November 1973), pp. 689.

ROUTINES CALLED
(NONE)

COMMON BLOCKS
CCBLK

REVISION HISTORY (YYMMDD)
801001 DATE WRITTEN
890831 Modified array declarations. (WRB)
891214 Prologue converted to Version 4.0 format. (BAB)
900402 Added TYPE section. (WRB)
920528 DESCRIPTION revised and REFERENCES section added. (WRB)