SOLRN (3sciport)

Solves a second order linear recurrence for the last term

SYNOPSIS

  result = SOLRN( n, x, incx, y, incy, z, incz )

FUNCTION VALUE

  solrn           Real.
                  The last term of the linear recurrence.

ARGUMENTS

  n               Integer.
                  The length of the linear recurrence.

  x               Real vector.
                  An input vector of length n.

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

  y               Real vector.
                  An input vector of length n.

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

  z               Real vector.
                  A result vector of length n.

  incz            Integer.
                  The increment between elements of vector z. For contiguous
                  elements, incz = 1.

DESCRIPTION

  A real function that solves for the last term of a second-order linear
  recurrence using input vectors x and y and result vector z.  It has the
  form:

          DO I = 3,N
             Z(I) = X(I-2)*Z(I-1) + Y(I-2)*Z(I-2)
          ENDDO
          SOLRN = Z(N)

  Z(1) and Z(2) are input to the routine, and Z(3) to Z(N) are output from
  the routine.

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