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C $Header: /u/gcmpack/MITgcm/model/src/cg2d.F,v 1.54 2011/06/08 01:46:34 jmc Exp $ |
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C $Name: $ |
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|
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#include "CPP_OPTIONS.h" |
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#ifdef TARGET_NEC_SX |
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C set a sensible default for the outer loop unrolling parameter that can |
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C be overriden in the Makefile with the DEFINES macro or in CPP_OPTIONS.h |
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#ifndef CG2D_OUTERLOOPITERS |
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# define CG2D_OUTERLOOPITERS 10 |
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#endif |
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#endif /* TARGET_NEC_SX */ |
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|
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CBOP |
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C !ROUTINE: CG2D |
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C !INTERFACE: |
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SUBROUTINE CG2D( |
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U cg2d_b, cg2d_x, |
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O firstResidual, minResidualSq, lastResidual, |
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U numIters, nIterMin, |
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I myThid ) |
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C !DESCRIPTION: \bv |
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C *==========================================================* |
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C | SUBROUTINE CG2D |
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C | o Two-dimensional grid problem conjugate-gradient |
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C | inverter (with preconditioner). |
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C *==========================================================* |
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C | Con. grad is an iterative procedure for solving Ax = b. |
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C | It requires the A be symmetric. |
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C | This implementation assumes A is a five-diagonal |
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C | matrix of the form that arises in the discrete |
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C | representation of the del^2 operator in a |
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C | two-dimensional space. |
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C | Notes: |
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C | ====== |
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C | This implementation can support shared-memory |
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C | multi-threaded execution. In order to do this COMMON |
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C | blocks are used for many of the arrays - even ones that |
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C | are only used for intermedaite results. This design is |
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C | OK if you want to all the threads to collaborate on |
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C | solving the same problem. On the other hand if you want |
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C | the threads to solve several different problems |
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C | concurrently this implementation will not work. |
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C *==========================================================* |
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C \ev |
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|
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C !USES: |
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IMPLICIT NONE |
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C === Global data === |
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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 "CG2D.h" |
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|
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C !INPUT/OUTPUT PARAMETERS: |
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C === Routine arguments === |
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C cg2d_b :: The source term or "right hand side" (output: normalised RHS) |
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C cg2d_x :: The solution (input: first guess) |
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C firstResidual :: the initial residual before any iterations |
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C minResidualSq :: the lowest residual reached (squared) |
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C lastResidual :: the actual residual reached |
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C numIters :: Inp: the maximum number of iterations allowed |
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C Out: the actual number of iterations used |
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C nIterMin :: Inp: decide to store (if >=0) or not (if <0) lowest res. sol. |
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C Out: iteration number corresponding to lowest residual |
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C myThid :: Thread on which I am working. |
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_RL cg2d_b(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy) |
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_RL cg2d_x(1-OLx:sNx+OLx,1-OLy:sNy+OLy,nSx,nSy) |
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_RL firstResidual |
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_RL minResidualSq |
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_RL lastResidual |
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INTEGER numIters |
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INTEGER nIterMin |
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INTEGER myThid |
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|
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C !LOCAL VARIABLES: |
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C === Local variables ==== |
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C bi, bj :: tile index in X and Y. |
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C i, j, it2d :: Loop counters ( it2d counts CG iterations ) |
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C actualIts :: actual CG iteration number |
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C err_sq :: Measure of the square of the residual of Ax - b. |
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C eta_qrN :: Used in computing search directions; suffix N and NM1 |
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C eta_qrNM1 denote current and previous iterations respectively. |
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C cgBeta :: coeff used to update conjugate direction vector "s". |
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C alpha :: coeff used to update solution & residual |
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C sumRHS :: Sum of right-hand-side. Sometimes this is a useful |
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C debugging/trouble shooting diagnostic. For neumann problems |
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C sumRHS needs to be ~0 or it converge at a non-zero residual. |
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C cg2d_min :: used to store solution corresponding to lowest residual. |
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C msgBuf :: Informational/error message buffer |
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INTEGER bi, bj |
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INTEGER i, j, it2d |
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INTEGER actualIts |
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_RL cg2dTolerance_sq |
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_RL err_sq, errTile(nSx,nSy) |
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_RL eta_qrN, eta_qrNtile(nSx,nSy) |
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_RL eta_qrNM1 |
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_RL cgBeta |
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_RL alpha, alphaTile(nSx,nSy) |
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_RL sumRHS, sumRHStile(nSx,nSy) |
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_RL rhsMax |
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_RL rhsNorm |
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_RL cg2d_min(1:sNx,1:sNy,nSx,nSy) |
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#ifdef CG2D_SINGLECPU_SUM |
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_RL localBuf(1:sNx,1:sNy,nSx,nSy) |
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#endif |
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CHARACTER*(MAX_LEN_MBUF) msgBuf |
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LOGICAL printResidual |
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CEOP |
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|
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C-- Initialise auxiliary constant, some output variable and inverter |
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cg2dTolerance_sq = cg2dTolerance*cg2dTolerance |
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minResidualSq = -1. _d 0 |
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eta_qrNM1 = 1. _d 0 |
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|
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C-- Normalise RHS |
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rhsMax = 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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cg2d_b(i,j,bi,bj) = cg2d_b(i,j,bi,bj)*cg2dNorm |
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rhsMax = MAX(ABS(cg2d_b(i,j,bi,bj)),rhsMax) |
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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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IF (cg2dNormaliseRHS) THEN |
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C- Normalise RHS : |
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_GLOBAL_MAX_RL( rhsMax, myThid ) |
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rhsNorm = 1. _d 0 |
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IF ( rhsMax .NE. 0. ) rhsNorm = 1. _d 0 / rhsMax |
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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_b(i,j,bi,bj) = cg2d_b(i,j,bi,bj)*rhsNorm |
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cg2d_x(i,j,bi,bj) = cg2d_x(i,j,bi,bj)*rhsNorm |
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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- end Normalise RHS |
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ENDIF |
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|
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C-- Update overlaps |
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CALL EXCH_XY_RL( cg2d_x, myThid ) |
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|
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C-- Initial residual calculation |
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DO bj=myByLo(myThid),myByHi(myThid) |
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DO bi=myBxLo(myThid),myBxHi(myThid) |
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IF ( nIterMin.GE.0 ) THEN |
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DO j=1,sNy |
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DO i=1,sNx |
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cg2d_min(i,j,bi,bj) = cg2d_x(i,j,bi,bj) |
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ENDDO |
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ENDDO |
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ENDIF |
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DO j=0,sNy+1 |
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DO i=0,sNx+1 |
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cg2d_s(i,j,bi,bj) = 0. |
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ENDDO |
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ENDDO |
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sumRHStile(bi,bj) = 0. _d 0 |
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errTile(bi,bj) = 0. _d 0 |
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#ifdef TARGET_NEC_SX |
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!CDIR OUTERUNROLL=CG2D_OUTERLOOPITERS |
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#endif /* TARGET_NEC_SX */ |
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DO j=1,sNy |
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DO i=1,sNx |
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cg2d_r(i,j,bi,bj) = cg2d_b(i,j,bi,bj) - |
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& (aW2d(i ,j ,bi,bj)*cg2d_x(i-1,j ,bi,bj) |
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& +aW2d(i+1,j ,bi,bj)*cg2d_x(i+1,j ,bi,bj) |
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& +aS2d(i ,j ,bi,bj)*cg2d_x(i ,j-1,bi,bj) |
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& +aS2d(i ,j+1,bi,bj)*cg2d_x(i ,j+1,bi,bj) |
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& +aC2d(i ,j ,bi,bj)*cg2d_x(i ,j ,bi,bj) |
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& ) |
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#ifdef CG2D_SINGLECPU_SUM |
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localBuf(i,j,bi,bj) = cg2d_r(i,j,bi,bj)*cg2d_r(i,j,bi,bj) |
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#else |
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errTile(bi,bj) = errTile(bi,bj) |
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& + cg2d_r(i,j,bi,bj)*cg2d_r(i,j,bi,bj) |
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sumRHStile(bi,bj) = sumRHStile(bi,bj) + cg2d_b(i,j,bi,bj) |
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#endif |
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ENDDO |
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ENDDO |
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ENDDO |
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ENDDO |
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CALL EXCH_S3D_RL( cg2d_r, 1, myThid ) |
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#ifdef CG2D_SINGLECPU_SUM |
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CALL GLOBAL_SUM_SINGLECPU_RL(localBuf, err_sq, 0, 0, myThid) |
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CALL GLOBAL_SUM_SINGLECPU_RL(cg2d_b, sumRHS, OLx, OLy, myThid) |
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#else |
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CALL GLOBAL_SUM_TILE_RL( errTile, err_sq, myThid ) |
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CALL GLOBAL_SUM_TILE_RL( sumRHStile, sumRHS, myThid ) |
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#endif |
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actualIts = 0 |
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firstResidual = SQRT(err_sq) |
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IF ( nIterMin.GE.0 ) THEN |
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nIterMin = 0 |
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minResidualSq = err_sq |
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ENDIF |
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|
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printResidual = .FALSE. |
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IF ( debugLevel .GE. debLevZero ) THEN |
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_BEGIN_MASTER( myThid ) |
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printResidual = printResidualFreq.GE.1 |
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WRITE(standardmessageunit,'(A,1P2E22.14)') |
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& ' cg2d: Sum(rhs),rhsMax = ', sumRHS,rhsMax |
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_END_MASTER( myThid ) |
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ENDIF |
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|
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IF ( err_sq .LT. cg2dTolerance_sq ) GOTO 11 |
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|
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C >>>>>>>>>>>>>>> BEGIN SOLVER <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< |
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DO 10 it2d=1, numIters |
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|
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C-- Solve preconditioning equation and update |
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C-- conjugate direction vector "s". |
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DO bj=myByLo(myThid),myByHi(myThid) |
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DO bi=myBxLo(myThid),myBxHi(myThid) |
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eta_qrNtile(bi,bj) = 0. _d 0 |
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#ifdef TARGET_NEC_SX |
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!CDIR OUTERUNROLL=CG2D_OUTERLOOPITERS |
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#endif /* TARGET_NEC_SX */ |
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DO j=1,sNy |
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DO i=1,sNx |
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cg2d_q(i,j,bi,bj) = |
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& pC(i ,j ,bi,bj)*cg2d_r(i ,j ,bi,bj) |
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& +pW(i ,j ,bi,bj)*cg2d_r(i-1,j ,bi,bj) |
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& +pW(i+1,j ,bi,bj)*cg2d_r(i+1,j ,bi,bj) |
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& +pS(i ,j ,bi,bj)*cg2d_r(i ,j-1,bi,bj) |
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& +pS(i ,j+1,bi,bj)*cg2d_r(i ,j+1,bi,bj) |
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CcnhDebugStarts |
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c cg2d_q(i,j,bi,bj) = cg2d_r(j ,j ,bi,bj) |
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CcnhDebugEnds |
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#ifdef CG2D_SINGLECPU_SUM |
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localBuf(i,j,bi,bj) = |
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& cg2d_q(i,j,bi,bj)*cg2d_r(i,j,bi,bj) |
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#else |
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eta_qrNtile(bi,bj) = eta_qrNtile(bi,bj) |
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& +cg2d_q(i,j,bi,bj)*cg2d_r(i,j,bi,bj) |
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#endif |
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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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#ifdef CG2D_SINGLECPU_SUM |
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CALL GLOBAL_SUM_SINGLECPU_RL( localBuf,eta_qrN,0,0,myThid ) |
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#else |
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CALL GLOBAL_SUM_TILE_RL( eta_qrNtile,eta_qrN,myThid ) |
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#endif |
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cgBeta = eta_qrN/eta_qrNM1 |
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CcnhDebugStarts |
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c WRITE(*,*) ' CG2D: Iteration ', it2d-1, |
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c & ' eta_qrN=', eta_qrN, ' beta=', cgBeta |
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CcnhDebugEnds |
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eta_qrNM1 = eta_qrN |
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|
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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_s(i,j,bi,bj) = cg2d_q(i,j,bi,bj) |
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& + cgBeta*cg2d_s(i,j,bi,bj) |
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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-- Do exchanges that require messages i.e. between processes. |
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CALL EXCH_S3D_RL( cg2d_s, 1, myThid ) |
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|
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C== Evaluate laplace operator on conjugate gradient vector |
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C== q = A.s |
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DO bj=myByLo(myThid),myByHi(myThid) |
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DO bi=myBxLo(myThid),myBxHi(myThid) |
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alphaTile(bi,bj) = 0. _d 0 |
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#ifdef TARGET_NEC_SX |
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!CDIR OUTERUNROLL=CG2D_OUTERLOOPITERS |
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#endif /* TARGET_NEC_SX */ |
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DO j=1,sNy |
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DO i=1,sNx |
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cg2d_q(i,j,bi,bj) = |
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& aW2d(i ,j ,bi,bj)*cg2d_s(i-1,j ,bi,bj) |
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& +aW2d(i+1,j ,bi,bj)*cg2d_s(i+1,j ,bi,bj) |
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& +aS2d(i ,j ,bi,bj)*cg2d_s(i ,j-1,bi,bj) |
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& +aS2d(i ,j+1,bi,bj)*cg2d_s(i ,j+1,bi,bj) |
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& +aC2d(i ,j ,bi,bj)*cg2d_s(i ,j ,bi,bj) |
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#ifdef CG2D_SINGLECPU_SUM |
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localBuf(i,j,bi,bj) = cg2d_s(i,j,bi,bj)*cg2d_q(i,j,bi,bj) |
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#else |
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alphaTile(bi,bj) = alphaTile(bi,bj) |
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& + cg2d_s(i,j,bi,bj)*cg2d_q(i,j,bi,bj) |
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#endif |
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ENDDO |
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ENDDO |
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ENDDO |
| 300 |
ENDDO |
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#ifdef CG2D_SINGLECPU_SUM |
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CALL GLOBAL_SUM_SINGLECPU_RL(localBuf, alpha, 0, 0, myThid) |
| 303 |
#else |
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CALL GLOBAL_SUM_TILE_RL( alphaTile, alpha, myThid ) |
| 305 |
#endif |
| 306 |
CcnhDebugStarts |
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c WRITE(*,*) ' CG2D: Iteration ', it2d-1, |
| 308 |
c & ' SUM(s*q)=', alpha, ' alpha=', eta_qrN/alpha |
| 309 |
CcnhDebugEnds |
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alpha = eta_qrN/alpha |
| 311 |
|
| 312 |
C== Update simultaneously solution and residual vectors (and Iter number) |
| 313 |
C Now compute "interior" points. |
| 314 |
DO bj=myByLo(myThid),myByHi(myThid) |
| 315 |
DO bi=myBxLo(myThid),myBxHi(myThid) |
| 316 |
errTile(bi,bj) = 0. _d 0 |
| 317 |
DO j=1,sNy |
| 318 |
DO i=1,sNx |
| 319 |
cg2d_x(i,j,bi,bj)=cg2d_x(i,j,bi,bj)+alpha*cg2d_s(i,j,bi,bj) |
| 320 |
cg2d_r(i,j,bi,bj)=cg2d_r(i,j,bi,bj)-alpha*cg2d_q(i,j,bi,bj) |
| 321 |
#ifdef CG2D_SINGLECPU_SUM |
| 322 |
localBuf(i,j,bi,bj) = cg2d_r(i,j,bi,bj)*cg2d_r(i,j,bi,bj) |
| 323 |
#else |
| 324 |
errTile(bi,bj) = errTile(bi,bj) |
| 325 |
& + cg2d_r(i,j,bi,bj)*cg2d_r(i,j,bi,bj) |
| 326 |
#endif |
| 327 |
ENDDO |
| 328 |
ENDDO |
| 329 |
ENDDO |
| 330 |
ENDDO |
| 331 |
actualIts = it2d |
| 332 |
|
| 333 |
#ifdef CG2D_SINGLECPU_SUM |
| 334 |
CALL GLOBAL_SUM_SINGLECPU_RL(localBuf, err_sq, 0, 0, myThid) |
| 335 |
#else |
| 336 |
CALL GLOBAL_SUM_TILE_RL( errTile, err_sq, myThid ) |
| 337 |
#endif |
| 338 |
IF ( printResidual ) THEN |
| 339 |
IF ( MOD( it2d-1, printResidualFreq ).EQ.0 ) THEN |
| 340 |
WRITE(msgBuf,'(A,I6,A,1PE21.14)') |
| 341 |
& ' cg2d: iter=', it2d, ' ; resid.= ', SQRT(err_sq) |
| 342 |
CALL PRINT_MESSAGE( msgBuf, standardMessageUnit, |
| 343 |
& SQUEEZE_RIGHT, myThid ) |
| 344 |
ENDIF |
| 345 |
ENDIF |
| 346 |
IF ( err_sq .LT. cg2dTolerance_sq ) GOTO 11 |
| 347 |
IF ( err_sq .LT. minResidualSq ) THEN |
| 348 |
C- Store lowest residual solution |
| 349 |
minResidualSq = err_sq |
| 350 |
nIterMin = it2d |
| 351 |
DO bj=myByLo(myThid),myByHi(myThid) |
| 352 |
DO bi=myBxLo(myThid),myBxHi(myThid) |
| 353 |
DO j=1,sNy |
| 354 |
DO i=1,sNx |
| 355 |
cg2d_min(i,j,bi,bj) = cg2d_x(i,j,bi,bj) |
| 356 |
ENDDO |
| 357 |
ENDDO |
| 358 |
ENDDO |
| 359 |
ENDDO |
| 360 |
ENDIF |
| 361 |
|
| 362 |
CALL EXCH_S3D_RL( cg2d_r, 1, myThid ) |
| 363 |
|
| 364 |
10 CONTINUE |
| 365 |
11 CONTINUE |
| 366 |
|
| 367 |
IF ( nIterMin.GE.0 .AND. err_sq .GT. minResidualSq ) THEN |
| 368 |
C- use the lowest residual solution (instead of current one = last residual) |
| 369 |
DO bj=myByLo(myThid),myByHi(myThid) |
| 370 |
DO bi=myBxLo(myThid),myBxHi(myThid) |
| 371 |
DO j=1,sNy |
| 372 |
DO i=1,sNx |
| 373 |
cg2d_x(i,j,bi,bj) = cg2d_min(i,j,bi,bj) |
| 374 |
ENDDO |
| 375 |
ENDDO |
| 376 |
ENDDO |
| 377 |
ENDDO |
| 378 |
ENDIF |
| 379 |
|
| 380 |
IF (cg2dNormaliseRHS) THEN |
| 381 |
C-- Un-normalise the answer |
| 382 |
DO bj=myByLo(myThid),myByHi(myThid) |
| 383 |
DO bi=myBxLo(myThid),myBxHi(myThid) |
| 384 |
DO j=1,sNy |
| 385 |
DO i=1,sNx |
| 386 |
cg2d_x(i,j,bi,bj) = cg2d_x(i,j,bi,bj)/rhsNorm |
| 387 |
ENDDO |
| 388 |
ENDDO |
| 389 |
ENDDO |
| 390 |
ENDDO |
| 391 |
ENDIF |
| 392 |
|
| 393 |
C-- Return parameters to caller |
| 394 |
lastResidual = SQRT(err_sq) |
| 395 |
numIters = actualIts |
| 396 |
|
| 397 |
CcnhDebugStarts |
| 398 |
c _EXCH_XY_RL(cg2d_x, myThid ) |
| 399 |
c CALL PLOT_FIELD_XYRL( cg2d_x, 'CALC_MOM_RHS CG2D_X' , 1, myThid ) |
| 400 |
c err_sq = 0. _d 0 |
| 401 |
c DO bj=myByLo(myThid),myByHi(myThid) |
| 402 |
c DO bi=myBxLo(myThid),myBxHi(myThid) |
| 403 |
c DO j=1,sNy |
| 404 |
c DO i=1,sNx |
| 405 |
c cg2d_r(i,j,bi,bj) = cg2d_b(i,j,bi,bj) - |
| 406 |
c & (aW2d(i ,j ,bi,bj)*cg2d_x(i-1,j ,bi,bj) |
| 407 |
c & +aW2d(i+1,j ,bi,bj)*cg2d_x(i+1,j ,bi,bj) |
| 408 |
c & +aS2d(i ,j ,bi,bj)*cg2d_x(i ,j-1,bi,bj) |
| 409 |
c & +aS2d(i ,j+1,bi,bj)*cg2d_x(i ,j+1,bi,bj) |
| 410 |
c & +aC2d(i ,j ,bi,bj)*cg2d_x(i ,j ,bi,bj) |
| 411 |
c & ) |
| 412 |
c err_sq = err_sq + cg2d_r(i,j,bi,bj)*cg2d_r(i,j,bi,bj) |
| 413 |
c ENDDO |
| 414 |
c ENDDO |
| 415 |
c ENDDO |
| 416 |
c ENDDO |
| 417 |
c _GLOBAL_SUM_RL( err_sq, myThid ) |
| 418 |
c write(*,*) 'cg2d: Ax - b = ',SQRT(err_sq) |
| 419 |
CcnhDebugEnds |
| 420 |
|
| 421 |
RETURN |
| 422 |
END |
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