FOLRN (3sciport)

Solves the last term of a first order linear recurrence

SYNOPSIS

  result = FOLRN( n, x, incx, y, incy )

FUNCTION VALUE

  folrn           Real.
                  The last term of a first order linear recurrence.

ARGUMENTS

  n               Integer.
                  The length of the linear recurrence.

  x               Real vector.
                  An input vector of length n (x(1) is arbitrary.).

  incx            Integer.
                  The increment between elements of vector x. For contiguous
                  elements, incx = 1.

  y               Real vector.
                  An input/output vector of length n (The output overwrites
                  the input.).

  incy            Integer.
                  The increment between elements of vector y. For contiguous
                  elements, incy = 1.

DESCRIPTION

  A real function that solves for the last term of a first-order linear
  recurrence where vector y is overwritten by the result. It has the form:

          DO I = 2,N
             Y(I) = Y(I) - X(I)*Y(I-1)
          ENDDO

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