ADAS Subroutine sp5

      FUNCTION SP5(P,X)
C-----------------------------------------------------------------------
C
C  ******************** FORTRAN 77 FUNCTION: SP5 ***********************
C
C  PURPOSE:  TO CALCULATE A SPLINE THROUGH THE FIVE KNOT POINTS
C
C  CALLING PROGRAM:
C        OMEUPS
C
C
C  INPUT:   
C        (R*8) P    - THE FIVE KNOT POINTS
C        (R*8) X    - THE POINT AT WHICH TO EVALUATE THE SPLINE
C  OUTPUT:   
C        (R*8) SP5  - THE EVALUATED SPLINE
C
C  ROUTINES: NONE
C
C  DATE:     21/06/95				VERSION 1.1
C  AUTHOR:   A.LANZAFAME (UNIV. OF STRATHCLYDE) & D.H.BROOKS
C
C  DATE:     13/05/99				VERSION 1.2
C  AUTHOR:   HUGH SUMMERS, UNIVERSITY OF STRATHCLYDE
C            CORRECTED SERIOUS ERROR IN IF JUMPS AND MODIFICATION OF 
C            INPUT VARIABLE X ON RETURN.  MADE CONSTANTS DOUBLE PREC.
C
C
C------------------------------------------------------------------------
      REAL*8              P(5),        X