cs_grid.h

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#ifndef __CS_GRID_H__
#define __CS_GRID_H__

/*============================================================================
 * Grid connectivity and data used for multigrid coarsening
 * and associated matrix construction.
 *============================================================================*/

/*
  This file is part of Code_Saturne, a general-purpose CFD tool.

  Copyright (C) 1998-2021 EDF S.A.

  This program is free software; you can redistribute it and/or modify it under
  the terms of the GNU General Public License as published by the Free Software
  Foundation; either version 2 of the License, or (at your option) any later
  version.

  This program is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  details.

  You should have received a copy of the GNU General Public License along with
  this program; if not, write to the Free Software Foundation, Inc., 51 Franklin
  Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/

/*----------------------------------------------------------------------------*/

/*----------------------------------------------------------------------------
 * Local headers
 *----------------------------------------------------------------------------*/

#include "cs_base.h"

#include "cs_halo.h"
#include "cs_matrix.h"

/*----------------------------------------------------------------------------*/

BEGIN_C_DECLS

/*============================================================================
 * Macro definitions
 *============================================================================*/

/*============================================================================
 * Type definitions
 *============================================================================*/

/* Aggregation algorithm */

typedef enum {

  CS_GRID_COARSENING_DEFAULT,        
  CS_GRID_COARSENING_SPD_DX,         
  CS_GRID_COARSENING_SPD_MX,         
  CS_GRID_COARSENING_SPD_PW,         
  CS_GRID_COARSENING_CONV_DIFF_DX    
} cs_grid_coarsening_t;

/* Structure associated with opaque grid object */

typedef struct _cs_grid_t cs_grid_t;

/*============================================================================
 * Global variables
 *============================================================================*/

/* Names for coarsening options */

extern const char *cs_grid_coarsening_type_name[];

/*============================================================================
 * Semi-private function prototypes
 *
 * The following functions are intended to be used by the multigrid layer
 * (cs_multigrid.c), not directly by the user, so they are no more
 * documented than private static functions)
 *============================================================================*/

/*----------------------------------------------------------------------------
 * Create base grid by mapping from shared mesh values.
 *
 * Note that as arrays given as arguments are shared by the created grid
 * (which can only access them, not modify them), the grid should be
 * destroyed before those arrays.
 *
 * parameters:
 *   n_faces               <-- Local number of faces
 *   diag_block_size       <-- Block sizes for diagonal, or NULL
 *   extra_diag_block_size <-- Block sizes for extra diagonal, or NULL
 *   face_cell             <-- Face -> cells connectivity
 *   cell_cen              <-- Cell center (size: 3.n_cells_ext)
 *   cell_vol              <-- Cell volume (size: n_cells_ext)
 *   face_normal           <-- Internal face normals (size: 3.n_faces)
 *   a                     <-- Associated matrix
 *   a_conv                <-- Associated matrix (convection)
 *   a_diff                <-- Associated matrix (diffusion)
 *
 * returns:
 *   base grid structure
 *----------------------------------------------------------------------------*/

cs_grid_t *
cs_grid_create_from_shared(cs_lnum_t              n_faces,
                           const cs_lnum_t       *diag_block_size,
                           const cs_lnum_t       *extra_diag_block_size,
                           const cs_lnum_2_t     *face_cell,
                           const cs_real_t       *cell_cen,
                           const cs_real_t       *cell_vol,
                           const cs_real_t       *face_normal,
                           const cs_matrix_t     *a,
                           const cs_matrix_t     *a_conv,
                           const cs_matrix_t     *a_diff);

/*----------------------------------------------------------------------------
 * Create base grid by mapping from parent (possibly shared) matrix.
 *
 * Note that as arrays given as arguments are shared by the created grid
 * (which can only access them, not modify them), the grid should be
 * destroyed before those arrays.
 *
 * parameters:
 *   a       <-- associated matrix
 *   n_ranks <-- number of active ranks (<= 1 to restrict to local values)
 *
 * returns:
 *   base grid structure
 *----------------------------------------------------------------------------*/

cs_grid_t *
cs_grid_create_from_parent(const cs_matrix_t  *a,
                           int                 n_ranks);

/*----------------------------------------------------------------------------
 * Destroy a grid structure.
 *
 * parameters:
 *   grid <-> Pointer to grid structure pointer
 *----------------------------------------------------------------------------*/

void
cs_grid_destroy(cs_grid_t  **grid);

/*----------------------------------------------------------------------------
 * Free a grid structure's associated quantities.
 *
 * The quantities required to compute a coarser grid with relaxation from a
 * given grid are not needed after that stage, so may be freed.
 *
 * parameters:
 *   g <-> Pointer to grid structure
 *----------------------------------------------------------------------------*/

void
cs_grid_free_quantities(cs_grid_t *g);

/*----------------------------------------------------------------------------
 * Get grid information.
 *
 * parameters:
 *   g          <-- Grid structure
 *   level      --> Level in multigrid hierarchy (or NULL)
 *   symmetric  --> Symmetric matrix coefficients indicator (or NULL)
 *   db_size    --> Size of the diagonal block (or NULL)
 *   eb_size    --> Size of the extra diagonal block (or NULL)
 *   n_ranks    --> number of ranks with data (or NULL)
 *   n_rows     --> Number of local rows (or NULL)
 *   n_cols_ext --> Number of columns including ghosts (or NULL)
 *   n_entries  --> Number of entries (or NULL)
 *   n_g_rows   --> Number of global rows (or NULL)
 *----------------------------------------------------------------------------*/

void
cs_grid_get_info(const cs_grid_t  *g,
                 int              *level,
                 bool             *symmetric,
                 cs_lnum_t        *db_size,
                 cs_lnum_t        *eb_size,
                 int              *n_ranks,
                 cs_lnum_t        *n_rows,
                 cs_lnum_t        *n_cols_ext,
                 cs_lnum_t        *n_entries,
                 cs_gnum_t        *n_g_rows);

/*----------------------------------------------------------------------------
 * Get number of rows corresponding to a grid.
 *
 * parameters:
 *   g <-- Grid structure
 *
 * returns:
 *   number of rows of grid structure
 *----------------------------------------------------------------------------*/

cs_lnum_t
cs_grid_get_n_rows(const cs_grid_t  *g);

/*----------------------------------------------------------------------------
 * Get number of extended (local + ghost) columns corresponding to a grid.
 *
 * parameters:
 *   g <-- Grid structure
 *
 * returns:
 *   number of extended columns of grid structure
 *----------------------------------------------------------------------------*/

cs_lnum_t
cs_grid_get_n_cols_ext(const cs_grid_t  *g);

/*----------------------------------------------------------------------------
 * Get maximum number of extended (local + ghost) columns corresponding to
 * a grid, both with and without merging between ranks
 *
 * parameters:
 *   g <-- Grid structure
 *
 * returns:
 *   maximum number of extended columns of grid structure, with or without
 *   merging
 *----------------------------------------------------------------------------*/

cs_lnum_t
cs_grid_get_n_cols_max(const cs_grid_t  *g);

/*----------------------------------------------------------------------------
 * Get global number of rows corresponding to a grid.
 *
 * parameters:
 *   g <-- Grid structure
 *
 * returns:
 *   global number of rows of grid structure
 *----------------------------------------------------------------------------*/

cs_gnum_t
cs_grid_get_n_g_rows(const cs_grid_t  *g);

/*----------------------------------------------------------------------------
 * Get grid's associated matrix information.
 *
 * parameters:
 *   g <-- Grid structure
 *
 * returns:
 *   pointer to matrix structure
 *----------------------------------------------------------------------------*/

const cs_matrix_t *
cs_grid_get_matrix(const cs_grid_t  *g);

#if defined(HAVE_MPI)

/*----------------------------------------------------------------------------
 * Get the MPI subcommunicator for a given grid.
 *
 * parameters:
 *   g <-- Grid structure
 *
 * returns:
 *   MPI communicator
 *----------------------------------------------------------------------------*/

MPI_Comm
cs_grid_get_comm(const cs_grid_t  *g);

/*----------------------------------------------------------------------------
 * Get the MPI subcommunicator for a given merge stride.
 *
 * parameters:
 *   parent       <-- parent MPI communicator
 *   merge_stride <-- associated merge stride
 *
 * returns:
 *   MPI communicator
 *----------------------------------------------------------------------------*/

MPI_Comm
cs_grid_get_comm_merge(MPI_Comm  parent,
                       int       merge_stride);

#endif

/*----------------------------------------------------------------------------
 * Create coarse grid from fine grid.
 *
 * parameters:
 *   f                          <-- Fine grid structure
 *   coarsening_type            <-- Coarsening criteria type
 *   aggregation_limit          <-- Maximum allowed fine rows per coarse rows
 *   verbosity                  <-- Verbosity level
 *   merge_stride               <-- Associated merge stride
 *   merge_rows_mean_threshold  <-- mean number of rows under which
 *                                  merging should be applied
 *   merge_rows_glob_threshold  <-- global number of rows under which
 *                                  merging should be applied
 *   relaxation_parameter       <-- P0/P1 relaxation factor
 *
 * returns:
 *   coarse grid structure
 *----------------------------------------------------------------------------*/

cs_grid_t *
cs_grid_coarsen(const cs_grid_t  *f,
                int               coarsening_type,
                int               aggregation_limit,
                int               verbosity,
                int               merge_stride,
                int               merge_rows_mean_threshold,
                cs_gnum_t         merge_rows_glob_threshold,
                double            relaxation_parameter);

/*----------------------------------------------------------------------------
 * Create coarse grid with only one row per rank from fine grid.
 *
 * parameters:
 *   f            <-- Fine grid structure
 *   merge_stride <-- Associated merge stride
 *   verbosity    <-- Verbosity level
 *
 * returns:
 *   coarse grid structure
 *----------------------------------------------------------------------------*/

cs_grid_t *
cs_grid_coarsen_to_single(const cs_grid_t  *f,
                          int               merge_stride,
                          int               verbosity);

/*----------------------------------------------------------------------------
 * Compute coarse row variable values from fine row values
 *
 * parameters:
 *   f       <-- Fine grid structure
 *   c       <-- Fine grid structure
 *   f_var   <-- Variable defined on fine grid rows
 *   c_var   --> Variable defined on coarse grid rows
 *
 * returns:
 *   coarse grid structure
 *----------------------------------------------------------------------------*/

void
cs_grid_restrict_row_var(const cs_grid_t  *f,
                         const cs_grid_t  *c,
                         const cs_real_t  *f_var,
                         cs_real_t        *c_var);

/*----------------------------------------------------------------------------
 * Compute fine row variable values from coarse row values
 *
 * parameters:
 *   c       <-- Fine grid structure
 *   f       <-- Fine grid structure
 *   c_var   --> Variable defined on coarse grid rows
 *   f_var   <-- Variable defined on fine grid rows
 *----------------------------------------------------------------------------*/

void
cs_grid_prolong_row_var(const cs_grid_t  *c,
                        const cs_grid_t  *f,
                        cs_real_t        *c_var,
                        cs_real_t        *f_var);

/*----------------------------------------------------------------------------
 * Project coarse grid row numbers to base grid.
 *
 * If a global coarse grid row number is larger than max_num, its
 * value modulo max_num is used.
 *
 * parameters:
 *   g           <-- Grid structure
 *   n_base_rows <-- Number of rows in base grid
 *   max_num     <-- Values of c_row_num = global_num % max_num
 *   c_row_num   --> Global coarse row number (modulo max_num)
 *----------------------------------------------------------------------------*/

void
cs_grid_project_row_num(const cs_grid_t  *g,
                        cs_lnum_t         n_base_rows,
                        int               max_num,
                        int               c_row_num[]);

/*----------------------------------------------------------------------------
 * Project coarse grid row rank to base grid.
 *
 * parameters:
 *   g           <-- Grid structure
 *   n_base_rows <-- Number of rows in base grid
 *   f_row_rank  --> Global coarse row rank projected to fine rows
 *----------------------------------------------------------------------------*/

void
cs_grid_project_row_rank(const cs_grid_t  *g,
                         cs_lnum_t         n_base_rows,
                         int               f_row_rank[]);

/*----------------------------------------------------------------------------
 * Project variable from coarse grid to base grid
 *
 * parameters:
 *   g           <-- Grid structure
 *   n_base_rows <-- Number of rows in base grid
 *   c_var       <-- Row variable on coarse grid
 *   f_var       --> Row variable projected to fine grid
 *----------------------------------------------------------------------------*/

void
cs_grid_project_var(const cs_grid_t  *g,
                    cs_lnum_t         n_base_rows,
                    const cs_real_t   c_var[],
                    cs_real_t         f_var[]);

/*----------------------------------------------------------------------------
 * Compute diagonal dominance metric and project it to base grid
 *
 * parameters:
 *   g           <-- Grid structure
 *   n_base_rows <-- Number of rows in base grid
 *   diag_dom    --> Diagonal dominance metric (on fine grid)
 *----------------------------------------------------------------------------*/

void
cs_grid_project_diag_dom(const cs_grid_t  *g,
                         cs_lnum_t         n_base_rows,
                         cs_real_t         diag_dom[]);

/*----------------------------------------------------------------------------
 * Finalize global info related to multigrid solvers
 *----------------------------------------------------------------------------*/

void
cs_grid_finalize(void);

/*----------------------------------------------------------------------------
 * Dump grid structure
 *
 * parameters:
 *   g <-- grid structure that should be dumped
 *----------------------------------------------------------------------------*/

void
cs_grid_dump(const cs_grid_t  *g);

/*=============================================================================
 * Public function prototypes
 *============================================================================*/

/*----------------------------------------------------------------------------
 * Set matrix tuning behavior for multigrid coarse meshes.
 *
 * The finest mesh (level 0) is handled by the default tuning options,
 * so only coarser meshes are considered here.
 *
 * parameters:
 *   fill_type <-- associated matrix fill type
 *   max_level <-- maximum level for which tuning is active
 *----------------------------------------------------------------------------*/

void
cs_grid_set_matrix_tuning(cs_matrix_fill_type_t  fill_type,
                          int                    max_level);

/*----------------------------------------------------------------------------*/

END_C_DECLS

#endif /* __CS_GRID_H__ */