1: /*
  2:  * ex193.c
  3:  *
  4:  *  Created on: Jul 29, 2015
  5:  *      Author: Fande Kong fdkong.jd@gmail.com
  6:  */
  7: /*
  8:  * An example demonstrates how to use hierarchical partitioning approach
  9:  */

 11: #include <petscmat.h>

 13: static char help[] = "Illustrates use of hierarchical partitioning.\n";

 15: int main(int argc,char **args)
 16: {
 17:   Mat             A;                      /* matrix */
 18:   PetscInt        m,n;                    /* mesh dimensions in x- and y- directions */
 19:   PetscInt        i,j,Ii,J,Istart,Iend;
 20:   PetscErrorCode  ierr;
 21:   PetscMPIInt     size;
 22:   PetscScalar     v;
 23:   MatPartitioning part;
 24:   IS              coarseparts,fineparts;
 25:   IS              is,isn,isrows;
 26:   MPI_Comm        comm;

 28:   PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr;
 29:   comm = PETSC_COMM_WORLD;
 30:   MPI_Comm_size(comm,&size);
 31:   PetscOptionsBegin(comm,NULL,"ex193","hierarchical partitioning");
 32:   m = 15;
 33:   PetscOptionsInt("-M","Number of mesh points in the x-direction","partitioning",m,&m,NULL);
 34:   n = 15;
 35:   PetscOptionsInt("-N","Number of mesh points in the y-direction","partitioning",n,&n,NULL);
 36:   PetscOptionsEnd();

 38:   /*
 39:      Assemble the matrix for the five point stencil (finite difference), YET AGAIN
 40:   */
 41:   MatCreate(comm,&A);
 42:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n);
 43:   MatSetFromOptions(A);
 44:   MatSetUp(A);
 45:   MatGetOwnershipRange(A,&Istart,&Iend);
 46:   for (Ii=Istart; Ii<Iend; Ii++) {
 47:     v = -1.0; i = Ii/n; j = Ii - i*n;
 48:     if (i>0)   {J = Ii - n; MatSetValues(A,1,&Ii,1,&J,&v,INSERT_VALUES);}
 49:     if (i<m-1) {J = Ii + n; MatSetValues(A,1,&Ii,1,&J,&v,INSERT_VALUES);}
 50:     if (j>0)   {J = Ii - 1; MatSetValues(A,1,&Ii,1,&J,&v,INSERT_VALUES);}
 51:     if (j<n-1) {J = Ii + 1; MatSetValues(A,1,&Ii,1,&J,&v,INSERT_VALUES);}
 52:     v = 4.0; MatSetValues(A,1,&Ii,1,&Ii,&v,INSERT_VALUES);
 53:   }
 54:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 55:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
 56:   MatView(A,PETSC_VIEWER_STDOUT_WORLD);
 57:   /*
 58:    Partition the graph of the matrix
 59:   */
 60:   MatPartitioningCreate(comm,&part);
 61:   MatPartitioningSetAdjacency(part,A);
 62:   MatPartitioningSetType(part,MATPARTITIONINGHIERARCH);
 63:   MatPartitioningHierarchicalSetNcoarseparts(part,2);
 64:   MatPartitioningHierarchicalSetNfineparts(part,4);
 65:   MatPartitioningSetFromOptions(part);
 66:   /* get new processor owner number of each vertex */
 67:   MatPartitioningApply(part,&is);
 68:   /* coarse parts */
 69:   MatPartitioningHierarchicalGetCoarseparts(part,&coarseparts);
 70:   ISView(coarseparts,PETSC_VIEWER_STDOUT_WORLD);
 71:   /* fine parts */
 72:   MatPartitioningHierarchicalGetFineparts(part,&fineparts);
 73:   ISView(fineparts,PETSC_VIEWER_STDOUT_WORLD);
 74:   /* partitioning */
 75:   ISView(is,PETSC_VIEWER_STDOUT_WORLD);
 76:   /* get new global number of each old global number */
 77:   ISPartitioningToNumbering(is,&isn);
 78:   ISView(isn,PETSC_VIEWER_STDOUT_WORLD);
 79:   ISBuildTwoSided(is,NULL,&isrows);
 80:   ISView(isrows,PETSC_VIEWER_STDOUT_WORLD);
 81:   ISDestroy(&is);
 82:   ISDestroy(&coarseparts);
 83:   ISDestroy(&fineparts);
 84:   ISDestroy(&isrows);
 85:   ISDestroy(&isn);
 86:   MatPartitioningDestroy(&part);
 87:   MatDestroy(&A);
 88:   PetscFinalize();
 89:   return ierr;
 90: }




 95: /*TEST

 97:    test:
 98:       nsize: 4
 99:       args: -mat_partitioning_hierarchical_Nfineparts 2
100:       requires: parmetis
101:       TODO: cannot run because parmetis does reproduce across all machines, probably due to nonportable random number generator

103: TEST*/