#include "dims.h"
C     SUBROUTINE NATFIX
!     use cons_module,only: kmax,imaxp4
C     ****
C     ****     ADVANCES PSI(CO2) BY ONE TIME STEP
C     ****
C     include "params.h"
C     include "fcom.h"
C     include "vscr.h"
C     include "index.h"
C     include "buff.h"
C     include "crates.h"
C     include "lowbnd.h"
C     include "phys.h"
C     include "compcom.h"
C     DIMENSION WNAT(ZKMXP)
C     WNAT =(/
C    + 1.9500E-12, 1.9600E-12, 1.9800E-12, 2.0200E-12, 2.0700E-12,
C    + 2.1700E-12, 2.3200E-12, 2.5500E-12, 2.9300E-12, 3.5300E-12,
C    + 4.4800E-12, 5.9900E-12, 8.3700E-12, 1.2100E-11, 1.8000E-11,
C    + 2.6700E-11, 3.7700E-11, 4.7400E-11, 5.2200E-11, 5.3000E-11,
C    + 5.1700E-11, 4.9600E-11, 4.6100E-11, 4.0500E-11, 3.3400E-11,
C    + 2.6200E-11, 1.9800E-11, 1.4600E-11, 1.0500E-11, 7.3900E-12,
C    + 5.0500E-12, 3.3500E-12, 2.1500E-12, 1.3200E-12, 7.8100E-13,
C    + 4.4200E-13, 2.4000E-13, 1.2600E-13, 6.3800E-14, 3.1400E-14,
C    + 1.5200E-14, 7.2000E-15, 3.3700E-15, 1.5600E-15, 7.2200E-16/)
C     NPNATK = NJ+NPNAT-1
C     NPNATMK = NJ+NPNATNM-1
C     DO 1 K=1,KMAX
C     NPNATK = NPNATK+1
C     NPNATMK = NPNATMK+1
C     DO 1 I=1,IMAXP4
C     F(I,NPNATK) = WNAT(K)
C     F(I,NPNATMK) = WNAT(K)
C  1  CONTINUE
C     RETURN
C     END
!-----------------------------------------------------------------------
      SUBROUTINE CMPNAT
      use cons_module,only: len1,len2
      implicit none
C     ****     ADVANCE NAT COMPOSITION BY ONE TIME STEP
c 1/2/97: changed var names from AR to NAT (NAT was previously tested 
c         in AR slot)
#include "params.h"
#include "fcom.h"
#include "vscr.h"
#include "index.h"
#include "buff.h"
#include "mwt.h"
#include "diffk.h"
#include "cmpdat.h"
!
! Local:
      real :: PHINAT(3)=(/1.042, 1.509, 1.176/)
      real,parameter :: ALFANAT=0.17, PSNATB=0.1146E-1,
     |                  AS=1.875E-3, ZPS=89.E+5, H1S=5.E+5
      integer :: ibnd,ibndb,i,k,nzk
      real :: xynat
C     ****     UPPER BOUNDARY - ZERO FLUX
C     ****     LOWER BOUNDARY - CONSTANT VALUE
      IBND = 1
C     IBNDB = 0
      IBNDB = 1
      DO 1 I=1,LEN1
      T4(I)=0.
      T1(I)=0.
      T2(I)=1.
C     T3(I)=-SQRT(WNAT(1)*WNAT(2))
      T3(I)=-1.5E+3
    1 CONTINUE
C     ****     SOURCES ARE METEORITES AND LOSSES ARE ZERO
      NZK=NJ+NZ
      DO 2 I=1,LEN2
      S2(I,1) = AS*EXP(-((F(I,NZK)-ZPS)/H1S)**2)
      S1(I,1) = 0.
    2 CONTINUE
      XYNAT = 1.E-10
      CALL MINOR(NPNAT,NPNATNM,RMNAT,PHINAT,ALFANAT,IBND,IBNDB,WNAT,
     | XYNAT,NPDHNAT,difkk,9)
C*************************************************
C     NPNATK = NJNP + NPNAT - 1
C     DO K = 1,KMAXP1,4
C       DO I = 1,IMAX
C         PLOT(I,J,K) = F(I+2,NPNATK + K)
C       ENDDO
C     ENDDO
C     IF(J.EQ.JMAX)THEN
C       DO K = 1,KMAXP1,4
C         CALL EZCNTR(PLOT(1,1,K),IMAX,JMAX)
C         WRITE(6,*)'K = ', K
C       ENDDO
C     ENDIF
C*************************************************
      RETURN
      END