C------------------------------------------------------------------------------
C ngrav.for
C------------------------------------------------------------------------------
C 25 Mar 2010 - Added argument gravity to CALL PGRAVg
C 23 Mar 2010 - Added CALL PGRAVg and CALL PGRAVa
C 23 Mar 2010 - Added argument gravity to ENTRY GRAVg
C 23 Mar 2010 - Added ENTRY GRAVg (with argument)
C 23 Mar 2010 - Added ENTRY GRAVa (without argument)
C 19 Mar 2008 - Changed GID to GVID for consistency
C 19 Jul 2006 - Separated igrav (no argument) and igravg (w. argument)
C 13 July 2006 - CORRECTIONS
C 12 July 2006
C------------------------------------------------------------------------------
      SUBROUTINE NGRAV
C------------------------------------------------------------------------------
C     GENERIC GRAVITY MODEL
      implicit double precision (a-h,o-z)
C
      TYPE :: model
         CHARACTER :: model_name
         REAL(KIND=8) :: data_id
         CHARACTER :: pert_name
         REAL(KIND=8) :: pert_id
      END TYPE model
      TYPE (model) :: modgg

C For gravity, the following variables represent first derivatives of the
C the three components (r, theta, and phi), NOT SECOND DERIVATIVES.
C Example: pthtm is the partial derivative of g_sub_th with respect to time.

      TYPE :: gravity_and_derivs_1
         REAL(KIND=8) :: gs,gsr,gsth,gsph
         REAL(KIND=8) :: ptm,pr,pth,pph
         REAL(KIND=8) :: prtm,prr,prth,prph
         REAL(KIND=8) :: pthtm,pthr,pthth,pthph
         REAL(KIND=8) :: pphtm,pphr,pphth,pphph
      END TYPE 
      TYPE (gravity_and_derivs_1) :: gravity

C     COMMON DECK "WW" INSERTED HERE
      common/ww/ dum(10),maxw,w(1000)
C
C     GRAVITY    600-624
      EQUIVALENCE (W(600),GVMODEL),(W(601),GFORM),(W(602),GVID)    ! 19 Mar 2008
C
C     COMMON DECK "GV" INSERTED HERE
      DOUBLE PRECISION modgv
      COMMON/GV/MODGV(4)
     1  ,GV  ,PGVTM  ,PGVR  ,PGVTH  ,PGVPH
     2  ,GVR ,PGVRTM ,PGVRR ,PGVRTH ,PGVRPH
     3  ,GVTH,PGVTHTM,PGVTHR,PGVTHTH,PGVTHPH
     4  ,GVPH,PGVPHTM,PGVPHR,PGVPHTH,PGVPHPH

C     COMMON DECK "B13" INSERTED HERE
      INTEGER TMX,TNTBL,TITBL,TFRMTBL,IDST(10)
      COMMON/B13/TMX,TNTBL(10),TITBL(10),TFRMTBL(10),TGP(262)
      EQUIVALENCE (TGP,IDST),(ANT,TGP(11))
      INTEGER TYMX,TYNTBL(10),TYITBL(10),TYFRMTBL(10)
C
      DATA RECOGG/0.d0/
      DATA TYMX/1/
      DATA TYNTBL/1,11,8*0/
      DATA TYITBL/1,9*0/
      DATA TYFRMTBL/1,9*0/
C                           
      ENTRY SETGRAV
      TMX=TYMX             
      CALL IMOVE(TNTBL,TYNTBL,10)  
      CALL IMOVE(TITBL,TYITBL,10)  
      CALL IMOVE(TFRMTBL,TYFRMTBL,10) ! 13 July 2006 
      CALL SETPGRAV ! 13 July 2006 
      RETURN                        
C
C------------------------------------------------------------------------------

      ENTRY IGRAV
      IF(idint(RECOGG) .NE. idint(GVMODEL))
     1    CALL RERROR('NGRAV  ','WRNG MODEL',RECOGG)
C
      MODGV(1)=5HNGRAV
      MODGV(2)=GVID                                                ! 19 Mar 2008
      CALL IPGRAV ! 13 July 2006 
      RETURN

C------------------------------------------------------------------------------

      ENTRY igravg(modgg) ! 19 Jul 2006
      IF (gvmodel /= 0.d0) THEN
           PRINT *,' Model check number mismatch: '
           STOP ' W(600) should be 0 if you are using model NGRAV.'
      ENDIF

      modgg%model_name = 'NGRAV'
      modgg%data_id = gvid
      modgg%pert_name = ''
      modgg%pert_id = 0.d0

      CALL ipgravg(modgg) ! 25 January 2006

      RETURN
C
C------------------------------------------------------------------------------

      ENTRY grav(gravity)                                       ! 23 Mar 2010
      ENTRY gravg(gravity)                                      ! 23 Mar 2010
      CALL PGRAVg(gravity)                                      ! 25 Mar 2010
      RETURN

      ENTRY GRAVa                                               ! 23 Mar 2010
      CALL PGRAVa                                               ! 23 Mar 2010
      RETURN
C------------------------------------------------------------------------------
      END SUBROUTINE NGRAV                                      ! 23 Mar 2010
C------------------------------------------------------------------------------