C	$Id: CG2D.h,v 1.3 2006/05/12 22:34:02 ce107 Exp $	
C
C     /==========================================================\
C     | CG2D.h                                                   |
C     | o Two-dimensional conjugate gradient solver header.      |
C     |==========================================================|
C     | The common blocks set up here are used in the elliptic   |
C     | equation inversion. They are also used as the interface  |
C     | to the rest of the model. To set the source term for the |
C     | solver set the appropriate array below. To read the      |
C     | solution read from the appropriate array below.          |
C     \==========================================================/

C--   COMMON /CG2D_R/ DEL**2 Laplacian operators
C     aW2d - East-west operator.
C     aS2d - North-south operator.
C     pW   - East-west off-diagonal term of preconditioner.
C     pS   - North-south off-diagonal term of preconditioner.
C     pC   - Main diagonal term of preconditioner.
      COMMON /CG2D_R/
     &      aW2d,
     &      aS2d,
     &      pW, pS, pC
      Real aW2d (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      Real aS2d (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      Real pW   (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      Real pS   (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      Real pC   (1-OLx:sNx+OLx,1-OLy:sNy+OLy)

C--   COMMON /CG2D_WK_R/  Work array common block
C     cg2d_q - Intermediate matrix-vector product term
C     cg2d_r -   "
C     cg2d_s -   "
C     cg2d_x   Solution vector
C     cg2d_Ax  Laplace operator on the solution (used to check
C              the result).
C     cg2d_b   Right-hand side vector
      COMMON /CG2D_WK_R/
     & cg2d_q, cg2d_r, cg2d_s, cg2d_x, cg2d_Ax, cg2d_b
      Real cg2d_q(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      Real cg2d_r(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      Real cg2d_s(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      Real cg2d_x (1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      Real cg2d_Ax(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
      Real cg2d_b(1-OLx:sNx+OLx,1-OLy:sNy+OLy)