Files
GEOS-Chem-adjoint-v35-note/code/backsub.f
2018-08-28 00:43:47 -04:00

315 lines
12 KiB
Fortran

! $Id: backsub.f,v 1.1 2009/06/09 21:51:53 daven Exp $
SUBROUTINE BACKSUB
!
!******************************************************************************
! Subroutine BACKSUB does the back-substitution on the decomposed matrix.
! (M. Jacobson 1997; bdf, bmy, 4/1/03, 7/9/03)
!
! NOTES:
! (1 ) Comment out counter variable NUM_BACKSUB, you can get the same info
! w/ a profiling run. (bmy, 7/9/03)
!******************************************************************************
!
IMPLICIT NONE
# include "CMN_SIZE" ! Size parameters
# include "comode.h" ! SMVGEAR II arrays
! Local variables
INTEGER IJ,I,KZT,KL5,KH5,KL4,KH4,KL3,KH3,KL2,KH2,KL1,KH1,KC
INTEGER J0,IJ0,IJ1,IJ2,IJ3,IJ4,J1,J2,J3,J4,K,MZT,ML5,MH5,ML4,MH4
INTEGER ML3,MH3,ML2,MH2,ML1,MH1,MC
C
C *********************************************************************
C ************ WRITTEN BY MARK JACOBSON (1993) ************
C *** (C) COPYRIGHT, 1993 BY MARK Z. JACOBSON ***
C *** U.S. COPYRIGHT OFFICE REGISTRATION NO. TXu 670-279 ***
C *** (650) 723-6836 ***
C *********************************************************************
C
C BBBBBBB A CCCCCCC K K SSSSSSS U U BBBBBBB
C B B A A C K K S U U B B
C BBBBBBB A A C K K SSSSSSS U U BBBBBBB
C B B AAAAAAA C K K S U U B B
C BBBBBBB A A CCCCCCC K K SSSSSSS UUUUUUUU BBBBBBB
C
C *********************************************************************
C ******* PERFORM BACK-SUBSTITUTIONS ON THE DECOMPOSED MATRIX *******
C *********************************************************************
C *********************************************************************
C * THIS SUBROUTINE SOLVES THE LINEAR SET OF EQUATIONS Ax = B FOR x, *
C * THE CORRECTION VECTOR, WHERE "A" IS THE L-U DECOMPOSTION OF THE *
C * ORIGINAL MATRIX, *
C * *
C * P = I - H x Bo x J, *
C * *
C * I = IDENTITY MATRIX, H = TIME-STEP, Bo = A COEFFICIENT THAT *
C * DEPENDS ON THE ORDER OF THE INTEGRATION METHOD, AND J IS THE *
C * MATRIX OF PARTIAL DERIVATIVES. B IS SENT FROM SMVGEAR AS A *
C * CORRECTED VALUE OF THE FIRST DERIVATIVES OF THE ORDINARY DIFFER- *
C * ENTIAL EQUATIONS. SUBROUTINE DECOMP.F SOLVED FOR "A", THE *
C * DECOMPOSED MATRIX. SEE PRESS ET AL. (1992) NUMERICAL RECIPES. *
C * CAMBRIDGE UNIVERSITY PRESS, FOR A BETTER DESCRIPTION OF THE BACK- *
C * SUBSTITUTION PROCESS. *
C * *
C * THIS BACK-SUBSTITUTION PROCESS USES SPARSE-MATRIX TECHNIQUES, *
C * VECTORIZES AROUND THE GRID-CELL DIMENSION, AND USES NO PARTIAL *
C * PIVOTING. TESTS BY SHERMAN & HINDMARSH (1980) LAWRENCE LIVERMORE *
C * REP. UCRL-84102 AND BY US HAVE CONFIRMED THAT THE REMOVAL OF *
C * PARTIAL PIVOTING HAS LITTLE EFFECT ON RESULTS. *
C * *
C * HOW TO CALL SUBROUTINE: *
C * ---------------------- *
C * CALL BACKSUB.F FROM SMVGEAR.F WITH *
C * NCS = 1..NCSGAS FOR GAS CHEMISTRY *
C * NCSP = NCS FOR DAYTIME GAS CHEM *
C * NCSP = NCS +ICS FOR NIGHTTIME GAS CHEM *
C *********************************************************************
C
C *********************************************************************
C * BACKSUB LOOP # 1 *
C * FIRST, ADJUST RIGHT SIDE OF Ax = B USING LOWER TRIANGULAR MATRIX *
C *********************************************************************
C SUM 1,2,3,4, OR 5 TERMS AT A TIME TO IMPROVE VECTORIZATION.
C
C KTLOOP = NUMBER OF GRID-CELLS IN A GRID-BLOCK
C ISCHAN = ORDER OF MATRIX
C CC2 = ARRAY HOLDING VALUES OF DECOMPOSED MATRIX.
C GLOSS = ARRAY INITIALLY HOLDING RIGHT SIDE OF EQUATION. THESE
C VALUES ARE CONVERTED TO THE SOLUTION DURING BACK-SUBSTITUTION.
C KZEROA,..= ARRAYS IDENTIFYING TERMS IN GLOSS ARRAY
C
IJ = 1
DO 310 KZT = KZTLO(NCSP), KZTHI(NCSP)
I = IKZTOT(KZT)
KL5 = KBL5( KZT)
KH5 = KBH5( KZT)
KL4 = KBL4( KZT)
KH4 = KBH4( KZT)
KL3 = KBL3( KZT)
KH3 = KBH3( KZT)
KL2 = KBL2( KZT)
KH2 = KBH2( KZT)
KL1 = KBL1( KZT)
KH1 = KBH1( KZT)
C
C *********************** SUM 5 TERMS AT A TIME *********************
C
DO 105 KC = KL5, KH5
IJ0 = IJ
IJ1 = IJ + 1
IJ2 = IJ + 2
IJ3 = IJ + 3
IJ4 = IJ + 4
IJ = IJ + 5
J0 = KZEROA(KC)
J1 = KZEROB(KC)
J2 = KZEROC(KC)
J3 = KZEROD(KC)
J4 = KZEROE(KC)
DO 100 K = 1, KTLOOP
GLOSS(K,I) = GLOSS(K,I)
1 - CC2(K,IJ0) * GLOSS(K,J0)
2 - CC2(K,IJ1) * GLOSS(K,J1)
3 - CC2(K,IJ2) * GLOSS(K,J2)
4 - CC2(K,IJ3) * GLOSS(K,J3)
5 - CC2(K,IJ4) * GLOSS(K,J4)
100 CONTINUE
105 CONTINUE
C
C *********************** SUM 4 TERMS AT A TIME *********************
C
DO 155 KC = KL4, KH4
IJ0 = IJ
IJ1 = IJ + 1
IJ2 = IJ + 2
IJ3 = IJ + 3
IJ = IJ + 4
J0 = KZEROA(KC)
J1 = KZEROB(KC)
J2 = KZEROC(KC)
J3 = KZEROD(KC)
DO 150 K = 1, KTLOOP
GLOSS(K,I) = GLOSS(K,I)
1 - CC2(K,IJ0) * GLOSS(K,J0)
2 - CC2(K,IJ1) * GLOSS(K,J1)
3 - CC2(K,IJ2) * GLOSS(K,J2)
4 - CC2(K,IJ3) * GLOSS(K,J3)
150 CONTINUE
155 CONTINUE
C
C *********************** SUM 3 TERMS AT A TIME *********************
C
DO 205 KC = KL3, KH3
IJ0 = IJ
IJ1 = IJ + 1
IJ2 = IJ + 2
IJ = IJ + 3
J0 = KZEROA(KC)
J1 = KZEROB(KC)
J2 = KZEROC(KC)
DO 200 K = 1, KTLOOP
GLOSS(K,I) = GLOSS(K,I)
1 - CC2(K,IJ0) * GLOSS(K,J0)
2 - CC2(K,IJ1) * GLOSS(K,J1)
3 - CC2(K,IJ2) * GLOSS(K,J2)
200 CONTINUE
205 CONTINUE
C
C *********************** SUM 2 TERMS AT A TIME *********************
C
DO 255 KC = KL2, KH2
IJ0 = IJ
IJ1 = IJ + 1
IJ = IJ + 2
J0 = KZEROA(KC)
J1 = KZEROB(KC)
DO 250 K = 1, KTLOOP
GLOSS(K,I) = GLOSS(K,I)
1 - CC2(K,IJ0) * GLOSS(K,J0)
2 - CC2(K,IJ1) * GLOSS(K,J1)
250 CONTINUE
255 CONTINUE
C
C *********************** SUM 1 TERM AT A TIME **********************
C
DO 305 KC = KL1, KH1
IJ0 = IJ
IJ = IJ + 1
J0 = KZEROA(KC)
DO 300 K = 1, KTLOOP
GLOSS(K,I) = GLOSS(K,I)
1 - CC2(K,IJ0) * GLOSS(K,J0)
300 CONTINUE
305 CONTINUE
310 CONTINUE
C
C *********************************************************************
C * BACKSUB LOOP # 2 *
C * BACKSUBSTITE WITH UPPER TRIANGULAR MATRIX TO FIND SOLUTION *
C *********************************************************************
C AGAIN, SUM UP SEVERAL TERMS AT A TIME TO IMPROVE VECTORIZATION.
C VDIAG = DIAGONAL TERM FROM L-U DECOMPOSTION.
C GLOSS = SOLUTION ON OUTPUT
C
DO 710 I = ISCHAN, 1, -1
MZT = IMZTOT(I,NCSP)
IF (MZT.GT.0) THEN
ML5 = MBL5( MZT)
MH5 = MBH5( MZT)
ML4 = MBL4( MZT)
MH4 = MBH4( MZT)
ML3 = MBL3( MZT)
MH3 = MBH3( MZT)
ML2 = MBL2( MZT)
MH2 = MBH2( MZT)
ML1 = MBL1( MZT)
MH1 = MBH1( MZT)
C
C *********************** SUM 5 TERMS AT A TIME *********************
C
DO 405 MC = ML5, MH5
IJ0 = IJ
IJ1 = IJ + 1
IJ2 = IJ + 2
IJ3 = IJ + 3
IJ4 = IJ + 4
IJ = IJ + 5
J0 = MZEROA(MC)
J1 = MZEROB(MC)
J2 = MZEROC(MC)
J3 = MZEROD(MC)
J4 = MZEROE(MC)
DO 400 K = 1, KTLOOP
GLOSS(K,I) = GLOSS(K,I)
1 - CC2(K,IJ0) * GLOSS(K,J0)
2 - CC2(K,IJ1) * GLOSS(K,J1)
3 - CC2(K,IJ2) * GLOSS(K,J2)
4 - CC2(K,IJ3) * GLOSS(K,J3)
5 - CC2(K,IJ4) * GLOSS(K,J4)
400 CONTINUE
405 CONTINUE
C
C *********************** SUM 4 TERMS AT A TIME *********************
C
DO 455 MC = ML4, MH4
IJ0 = IJ
IJ1 = IJ + 1
IJ2 = IJ + 2
IJ3 = IJ + 3
IJ = IJ + 4
J0 = MZEROA(MC)
J1 = MZEROB(MC)
J2 = MZEROC(MC)
J3 = MZEROD(MC)
DO 450 K = 1, KTLOOP
GLOSS(K,I) = GLOSS(K,I)
1 - CC2(K,IJ0) * GLOSS(K,J0)
2 - CC2(K,IJ1) * GLOSS(K,J1)
3 - CC2(K,IJ2) * GLOSS(K,J2)
4 - CC2(K,IJ3) * GLOSS(K,J3)
450 CONTINUE
455 CONTINUE
C
C *********************** SUM 3 TERMS AT A TIME *********************
C
DO 505 MC = ML3, MH3
IJ0 = IJ
IJ1 = IJ + 1
IJ2 = IJ + 2
IJ = IJ + 3
J0 = MZEROA(MC)
J1 = MZEROB(MC)
J2 = MZEROC(MC)
DO 500 K = 1, KTLOOP
GLOSS(K,I) = GLOSS(K,I)
1 - CC2(K,IJ0) * GLOSS(K,J0)
2 - CC2(K,IJ1) * GLOSS(K,J1)
3 - CC2(K,IJ2) * GLOSS(K,J2)
500 CONTINUE
505 CONTINUE
C
C *********************** SUM 2 TERMS AT A TIME *********************
C
DO 555 MC = ML2, MH2
IJ0 = IJ
IJ1 = IJ + 1
IJ = IJ + 2
J0 = MZEROA(MC)
J1 = MZEROB(MC)
DO 550 K = 1, KTLOOP
GLOSS(K,I) = GLOSS(K,I)
1 - CC2(K,IJ0) * GLOSS(K,J0)
2 - CC2(K,IJ1) * GLOSS(K,J1)
550 CONTINUE
555 CONTINUE
C
C *********************** SUM 1 TERM AT A TIME **********************
C
DO 605 MC = ML1, MH1
IJ0 = IJ
IJ = IJ + 1
J0 = MZEROA(MC)
DO 600 K = 1, KTLOOP
GLOSS(K,I) = GLOSS(K,I)
1 - CC2(K,IJ0) * GLOSS(K,J0)
600 CONTINUE
605 CONTINUE
ENDIF
C ENDIF MZT.GT.0
C
C *************** ADJUST GLOSS WITH DIAGONAL ELEMENT ****************
C
DO 700 K = 1, KTLOOP
GLOSS(K,I) = GLOSS(K,I) * VDIAG(K,I)
700 CONTINUE
710 CONTINUE
C
C *********************************************************************
C ******************** END OF SUBROUTINE BACKSUB **********************
C *********************************************************************
C
RETURN
END SUBROUTINE BACKSUB