SDTTRS (3sciport)

Solves a real valued tri-diagonal linear system with one right-hand side, using the matrix factored by SDTTRF.

SYNOPSIS

  Call SDTTRS( n, c, d, e, inct, b, incb, work, lwork, info )

ARGUMENTS

  n               Integer.
                  The dimension of the tri-diagonal matrix and the length of
                  the right-hand side vector b.

  c               Real vector.
                  A vector holding the first sub-diagonal band of the tri-
                  diagonal matrix.

  d               Real vector.
                  A vector holding the diagonal band of the tri-diagonal
                  matrix.

  e               Real vector.
                  A vector holding the first super-diagonal band of the tri-
                  diagonal matrix.

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

  b               Real vector.
                  An input/output real vector. On input, this vector holds
                  the right-hand side vector. On output, it holds the
                  solution vector.

  incb            Integer.
                  The increment between elements in vector b. Typically,
                  incb = 1 in which case, the elements of b are contiguous.

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

  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

  SDTTRS solves a real-valued tri-diagonal linear system with a single
  right-hand side vector using the c, d, e, and work vectors created by the
  SDTTRF routine.

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