ADAS Subroutine lgspc

       SUBROUTINE LGSPC(XA,N,C1,C2,C3,C4)
       IMPLICIT REAL*8(A-H,O-Z)
C-----------------------------------------------------------------------
C                                                                       
C  ************  FORTRAN 77 SUBROUTINE: LGSPC  *************************
C                                                                       
C  PURPOSE: GENERATE PRECURSORS OF SPLINE COEFFICIENTS SUITABLE FOR BOTH 
C  FORWARD AND BACKWARD INTERPOLATION
C
C  LARGER ARRAY DIMENSION VERSION OF NGSPC
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 AUTHOR:
C
C  ******* H.P.SUMMERS, JET         7 FEB 1989   **********
C
C UNIX-IDL CONVERSION:
C
C VERSION: 1.1                          DATE: 07-10-96
C MODIFIED: WILLIAM OSBORN
C               - FIRST CONVERTED.
C
C VERSION: 1.2                          DATE: 15-05-07
C MODIFIED: Allan Whiteford
C               - Updated comments as part of subroutine
C                 documentation production.
C
C----------------------------------------------------------------------
      INTEGER             N
      REAL*8              C1(40,39),   C2(40,39),   C3(40,39)
      REAL*8              C4(40,39),   XA(40)