FUNCTION DIFF(X,Y)
C
C     C.L.LAWSON AND R.J.HANSON, JET PROPULSION LABORATORY, 1973 JUNE 7
C     TO APPEAR IN ^SOLVING LEAST SQUARES PROBLEMS^, PRENTICE-HALL, 1974
C
      IMPLICIT REAL*8(A-H,O-Z)
      IMPLICIT INTEGER(I-N)
C
      DIFF = X - Y
      RETURN
      END