ADAS Subroutine b2gspc

       SUBROUTINE B2GSPC(XA,N,C1,C2,C3,C4)                              
C
       IMPLICIT REAL*8(A-H,O-Z)                                         
C-----------------------------------------------------------------------
C
C  ****************** FORTRAN77 SUBROUTINE : B2GSPC ********************
C
C PURPOSE:
C  SUBROUTINE TO GENERATE PRECURSORS OF SPLINE COEFFICIENTS SUITABLE
C  FOR BOTH FORWARD AND BACKWARD INTERPOLATION
C
C
C
C  INPUT
C      XA(I)=SET OF KNOTS
C      N=NUMBER OF KNOTS  (N.LE.20)
C  OUTPUT
C      C1(I,J)=1ST SPLINE COEFFICIENT PRECURSOR
C      C2(I,J)=2ND SPLINE COEFFICIENT PRECURSOR
C      C3(I,J)=3RD SPLINE COEFFICIENT PRECURSOR
C      C4(I,J)=4TH SPLINE COEFFICIENT PRECURSOR
C
C NOTES: THIS ROUTINE IS NOT YET PROPERLY ANNOTATED
C
C UNIX-IDL PORT:
C
C VERSION: 1.1                          DATE: 06-03-96
C MODIFIED: TIM HAMMOND (TESSELLA SUPPORT SERVICES PLC)
C               - PUT UNDER S.C.C.S. CONTROL
C
C-----------------------------------------------------------------------
C
      INTEGER             N
      REAL*8              C1(10,9),    C2(10,9),    C3(10,9)
      REAL*8              C4(10,9),    XA(10)