SLATEC Routines --- TRIS4 ---

*DECK TRIS4
      SUBROUTINE TRIS4 (N, A, B, C, D, U, Z)
C***BEGIN PROLOGUE  TRIS4
C***SUBSIDIARY
C***PURPOSE  Subsidiary to SEPX4
C***LIBRARY   SLATEC
C***TYPE      SINGLE PRECISION (TRIS4-S)
C***AUTHOR  (UNKNOWN)
C***DESCRIPTION
C
C     This subroutine solves for a non-zero eigenvector corresponding
C     to the zero eigenvalue of the transpose of the rank
C     deficient ONE matrix with subdiagonal A, diagonal B, and
C     superdiagonal C , with A(1) in the (1,N) position, with
C     C(N) in the (N,1) position, AND all other elements zero.
C
C***SEE ALSO  SEPX4
C***ROUTINES CALLED  (NONE)
C***REVISION HISTORY  (YYMMDD)
C   801001  DATE WRITTEN
C   890831  Modified array declarations.  (WRB)
C   891214  Prologue converted to Version 4.0 format.  (BAB)
C   900402  Added TYPE section.  (WRB)
C***END PROLOGUE  TRIS4