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C $Header: /u/gcmpack/models/MITgcmUV/model/src/ini_cg2d.F,v 1.8 1998/05/27 05:18:39 cnh Exp $ |
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#include "CPP_EEOPTIONS.h" |
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CStartOfInterface |
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SUBROUTINE INI_CG2D( myThid ) |
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C /==========================================================\ |
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C | SUBROUTINE INI_CG2D | |
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C | o Initialise 2d conjugate gradient solver operators. | |
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C |==========================================================| |
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C | These arrays are purely a function of the basin geom. | |
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C | We set then here once and them use then repeatedly. | |
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C \==========================================================/ |
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|
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C === Global variables === |
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#include "SIZE.h" |
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#include "EEPARAMS.h" |
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#include "PARAMS.h" |
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#include "GRID.h" |
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#include "CG2D.h" |
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|
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C === Routine arguments === |
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C myThid - Thread no. that called this routine. |
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INTEGER myThid |
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CEndOfInterface |
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|
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C === Local variables === |
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C xG, yG - Global coordinate location. |
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C zG |
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C iG, jG - Global coordinate index |
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C bi,bj - Loop counters |
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C faceArea - Temporary used to hold cell face areas. |
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C I,J,K |
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C myNorm - Work variable used in clculating normalisation factor |
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CHARACTER*(MAX_LEN_MBUF) msgBuf |
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INTEGER bi, bj |
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INTEGER I, J, K |
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_RL faceArea |
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_RL myNorm |
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_RL aC, aCw, aCs |
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|
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C-- Initialise laplace operator |
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C aW2d: integral in Z Ax/dX |
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C aS2d: integral in Z Ay/dY |
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myNorm = 0. _d 0 |
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DO bj=myByLo(myThid),myByHi(myThid) |
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DO bi=myBxLo(myThid),myBxHi(myThid) |
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DO J=1,sNy |
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DO I=1,sNx |
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aW2d(I,J,bi,bj) = 0. _d 0 |
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aS2d(I,J,bi,bj) = 0. _d 0 |
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ENDDO |
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ENDDO |
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DO K=1,Nz |
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DO J=1,sNy |
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DO I=1,sNx |
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faceArea = _dyG(I,J,bi,bj)*dzF(K)*HFacW(I,J,K,bi,bj) |
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aW2d(I,J,bi,bj) = aW2d(I,J,bi,bj) + |
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& gBaro*faceArea*rDxC(I,J,bi,bj) |
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faceArea = _dxG(I,J,bi,bj)*dzF(K)*HFacS(I,J,K,bi,bj) |
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aS2d(I,J,bi,bj) = aS2d(I,J,bi,bj) + |
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& gBaro*faceArea*rDyC(I,J,bi,bj) |
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ENDDO |
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ENDDO |
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ENDDO |
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DO J=1,sNy |
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DO I=1,sNx |
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myNorm = MAX(ABS(aW2d(I,J,bi,bj)),myNorm) |
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myNorm = MAX(ABS(aS2d(I,J,bi,bj)),myNorm) |
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ENDDO |
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ENDDO |
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ENDDO |
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ENDDO |
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cg2dNbuf(1,myThid) = myNorm |
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_GLOBAL_MAX_R8( cg2dNbuf, myNorm, myThid ) |
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IF ( cg2dNbuf(1,1) .NE. 0. _d 0 ) THEN |
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myNorm = 1. _d 0/cg2dNbuf(1,1) |
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ELSE |
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myNorm = 1. _d 0 |
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ENDIF |
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cg2dNorm = myNorm |
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_BEGIN_MASTER( myThid ) |
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CcnhDebugStarts |
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WRITE(msgBuf,'(A,F)') '// CG2D normalisation factor = ', cg2dNorm |
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CALL PRINT_MESSAGE( msgBuf,standardMessageUnit,SQUEEZE_RIGHT,1) |
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WRITE(msgBuf,*) ' ' |
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CALL PRINT_MESSAGE( msgBuf,standardMessageUnit,SQUEEZE_RIGHT,1) |
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CcnhDebugEnds |
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_END_MASTER( myThid ) |
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DO bj=myByLo(myThid),myByHi(myThid) |
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DO bi=myBxLo(myThid),myBxHi(myThid) |
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DO J=1,sNy |
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DO I=1,sNx |
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aW2d(I,J,bi,bj) = aW2d(I,J,bi,bj)*myNorm |
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aS2d(I,J,bi,bj) = aS2d(I,J,bi,bj)*myNorm |
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ENDDO |
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ENDDO |
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ENDDO |
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ENDDO |
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|
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C-- Update overlap regions |
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CcnhDebugStarts |
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C CALL PLOT_FIELD_XYR8( aW2d, 'AW2D INI_CG2D.1' , 1, myThid ) |
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C CALL PLOT_FIELD_XYR8( aS2d, 'AS2D INI_CG2D.1' , 1, myThid ) |
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CcnhDebugEnds |
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_EXCH_XY_R4(aW2d, myThid) |
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_EXCH_XY_R4(aS2d, myThid) |
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CcnhDebugStarts |
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C CALL PLOT_FIELD_XYR8( aW2d, 'AW2D INI_CG2D.2' , 1, myThid ) |
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C CALL PLOT_FIELD_XYR8( aS2d, 'AS2D INI_CG2D.2' , 1, myThid ) |
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CcnhDebugEnds |
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|
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C-- Initialise preconditioner |
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C Note. 20th May 1998 |
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C I made a weird discovery! In the model paper we argue |
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C for the form of the preconditioner used here ( see |
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C A Finite-volume, Incompressible Navier-Stokes Model |
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C ...., Marshall et. al ). The algebra gives a simple |
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C 0.5 factor for the averaging of ac and aCw to get a |
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C symmettric pre-conditioner. By using a factor of 0.51 |
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C i.e. scaling the off-diagonal terms in the |
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C preconditioner down slightly I managed to get the |
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C number of iterations for convergence in a test case to |
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C drop form 192 -> 134! Need to investigate this further! |
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C For now I have introduced a parameter cg2dpcOffDFac which |
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C defaults to 0.51 but can be set at runtime. |
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DO bj=myByLo(myThid),myByHi(myThid) |
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DO bi=myBxLo(myThid),myBxHi(myThid) |
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DO J=1,sNy |
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DO I=1,sNx |
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pC(I,J,bi,bj) = 1. _d 0 |
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aC = -( |
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& aW2d(I,J,bi,bj) + aW2d(I+1,J ,bi,bj) |
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& +aS2d(I,J,bi,bj) + aS2D(I ,J+1,bi,bj) |
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& +freeSurfFac*myNorm* |
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& zA(I,J,bi,bj)/deltaTMom/deltaTMom |
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& ) |
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aCs = -( |
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& aW2d(I,J-1,bi,bj) + aW2d(I+1,J-1,bi,bj) |
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& +aS2d(I,J-1,bi,bj) + aS2d(I ,J ,bi,bj) |
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& +freeSurfFac*myNorm* |
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& zA(I,J-1,bi,bj)/deltaTMom/deltaTMom |
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& ) |
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aCw = -( |
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& aW2d(I-1,J,bi,bj) + aW2d(I ,J ,bi,bj) |
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& +aS2d(I-1,J,bi,bj) + aS2d(I-1,J+1,bi,bj) |
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& +freeSurfFac*myNorm* |
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& zA(I-1,J,bi,bj)/deltaTMom/deltaTMom |
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& ) |
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IF ( aC .EQ. 0. ) THEN |
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pC(I,J,bi,bj) = 0. _d 0 |
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ELSE |
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pC(I,J,bi,bj) = 1. _d 0 / aC |
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ENDIF |
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IF ( aC + aCw .EQ. 0. ) THEN |
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pW(I,J,bi,bj) = 0. |
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ELSE |
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pW(I,J,bi,bj) = |
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& -aW2d(I ,J ,bi,bj)/((cg2dpcOffDFac *(aCw+aC))**2 ) |
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ENDIF |
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IF ( aC + aCs .EQ. 0. ) THEN |
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pS(I,J,bi,bj) = 0. |
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ELSE |
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pS(I,J,bi,bj) = |
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& -aS2d(I ,J ,bi,bj)/((cg2dpcOffDFac *(aCs+aC))**2 ) |
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ENDIF |
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C pC(I,J,bi,bj) = 1. |
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C pW(I,J,bi,bj) = 0. |
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C pS(I,J,bi,bj) = 0. |
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ENDDO |
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ENDDO |
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ENDDO |
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ENDDO |
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C-- Update overlap regions |
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_EXCH_XY_R4(pC, myThid) |
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_EXCH_XY_R4(pW, myThid) |
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_EXCH_XY_R4(pS, myThid) |
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|
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C-- Set default values for initial guess and RHS |
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IF ( startTime .EQ. 0 ) THEN |
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DO bj=myByLo(myThid),myByHi(myThid) |
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DO bi=myBxLo(myThid),myBxHi(myThid) |
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DO J=1,sNy |
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DO I=1,sNx |
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cg2d_x(I,J,bi,bj) = 0. _d 0 |
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cg2d_b(I,J,bi,bj) = 0. _d 0 |
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ENDDO |
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ENDDO |
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ENDDO |
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ENDDO |
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C-- Update overlap regions |
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_EXCH_XY_R8(cg2d_x, myThid) |
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_EXCH_XY_R8(cg2d_b, myThid) |
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ENDIF |
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|
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RETURN |
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END |
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