SDTTRF (3sciport)

Factors a real valued tri-diagonal linear system

SYNOPSIS

  Call SDTTRF( n, c, d, e, inct, work, lwork, info )

ARGUMENTS

  n               Integer.
                  The dimension of the tri-diagonal matrix.

  c               Real vector.
                  An input/output real vector holding the first sub-diagonal
                  band of the tri-diagonal matrix.

  d               Real vector.
                  An input/output real vector holding the diagonal band of
                  the tri-diagonal matrix.

  e               Real vector.
                  An input/output real vector holding the first super-
                  diagonal band of the tri-diagonal matrix.

  inct            Integer.
                  The increment between elements of vectors c, d, and e.

  work            Real vector.
                  A real output vector. This vector must not be modified
                  between calls to this routine and SDTTRS.

  lwork           Integer.
                  The length of vector work. lwork must be at least 2*n.

  info            Integer.
                  On exit, info has one of two values:
                      0 - no error detected,
                     -1 - lwork is too small.

DESCRIPTION

  SDTTRF factors a real-valued tri-diagonal linear system. The output of this
  routine, is contained in vectors c, d, e, and work. These vectors are input
  to SDTTRS where they are used to solve tri-diagonal linear systems.

  For equations and other information, see Volume 3: UNICOS Math and
  Scientific Library Reference Manual SR-2081 7.0, Cray Research, Inc.