2: static char help[] = "Tests MatCreateLRC()\n\n";

  4: /*T
  5:    Concepts: Low rank correction

  7:    Processors: n
  8: T*/

 10: #include <petscmat.h>

 14: int main(int argc,char **args)
 15: {
 16:   Vec            x,b;
 17:   Mat            A,U,V,LR;
 18:   PetscInt       i,j,Ii,J,Istart,Iend,m = 8,n = 7,rstart,rend;
 20:   PetscBool      flg;
 21:   PetscScalar    *u,a;

 23:   PetscInitialize(&argc,&args,(char*)0,help);
 24:   PetscOptionsGetInt(NULL,"-m",&m,NULL);
 25:   PetscOptionsGetInt(NULL,"-n",&n,NULL);

 27:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 28:          Create the sparse matrix
 29:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 30:   MatCreate(PETSC_COMM_WORLD,&A);
 31:   MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n);
 32:   MatSetFromOptions(A);
 33:   MatSetUp(A);
 34:   MatGetOwnershipRange(A,&Istart,&Iend);
 35:   for (Ii=Istart; Ii<Iend; Ii++) {
 36:     a = -1.0; i = Ii/n; j = Ii - i*n;
 37:     if (i>0)   {J = Ii - n; MatSetValues(A,1,&Ii,1,&J,&a,INSERT_VALUES);}
 38:     if (i<m-1) {J = Ii + n; MatSetValues(A,1,&Ii,1,&J,&a,INSERT_VALUES);}
 39:     if (j>0)   {J = Ii - 1; MatSetValues(A,1,&Ii,1,&J,&a,INSERT_VALUES);}
 40:     if (j<n-1) {J = Ii + 1; MatSetValues(A,1,&Ii,1,&J,&a,INSERT_VALUES);}
 41:     a = 4.0; MatSetValues(A,1,&Ii,1,&Ii,&a,INSERT_VALUES);
 42:   }
 43:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 44:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 46:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 47:          Create the dense matrices
 48:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 49:   MatCreate(PETSC_COMM_WORLD,&U);
 50:   MatSetSizes(U,PETSC_DECIDE,PETSC_DECIDE,m*n,3);
 51:   MatSetType(U,MATDENSE);
 52:   MatSetUp(U);
 53:   MatGetOwnershipRange(U,&rstart,&rend);
 54:   MatDenseGetArray(U,&u);
 55:   for (i=rstart; i<rend; i++) {
 56:     u[i-rstart]          = (PetscReal)i;
 57:     u[i+rend-2*rstart]   = (PetscReal)1000*i;
 58:     u[i+2*rend-3*rstart] = (PetscReal)100000*i;
 59:   }
 60:   MatDenseRestoreArray(U,&u);
 61:   MatAssemblyBegin(U,MAT_FINAL_ASSEMBLY);
 62:   MatAssemblyEnd(U,MAT_FINAL_ASSEMBLY);


 65:   MatCreate(PETSC_COMM_WORLD,&V);
 66:   MatSetSizes(V,PETSC_DECIDE,PETSC_DECIDE,m*n,3);
 67:   MatSetType(V,MATDENSE);
 68:   MatSetUp(V);
 69:   MatGetOwnershipRange(U,&rstart,&rend);
 70:   MatDenseGetArray(V,&u);
 71:   for (i=rstart; i<rend; i++) {
 72:     u[i-rstart]          = (PetscReal)i;
 73:     u[i+rend-2*rstart]   = (PetscReal)1.2*i;
 74:     u[i+2*rend-3*rstart] = (PetscReal)1.67*i+2;
 75:   }
 76:   MatDenseRestoreArray(V,&u);
 77:   MatAssemblyBegin(V,MAT_FINAL_ASSEMBLY);
 78:   MatAssemblyEnd(V,MAT_FINAL_ASSEMBLY);
 79:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 80:          Create low rank created matrix
 81:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 82:   MatCreateLRC(A,U,V,&LR);
 83:   MatSetUp(LR);

 85:   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 86:          Create test vectors
 87:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 88:   VecCreate(PETSC_COMM_WORLD,&x);
 89:   VecSetSizes(x,PETSC_DECIDE,m*n);
 90:   VecSetFromOptions(x);
 91:   VecDuplicate(x,&b);
 92:   VecGetOwnershipRange(x,&rstart,&rend);
 93:   VecGetArray(x,&u);
 94:   for (i=rstart; i<rend; i++) u[i-rstart] = (PetscScalar)i;
 95:   VecRestoreArray(x,&u);

 97:   MatMult(LR,x,b);
 98:   /*
 99:      View the product if desired
100:   */
101:   PetscOptionsHasName(NULL,"-view_product",&flg);
102:   if (flg) {VecView(b,PETSC_VIEWER_STDOUT_WORLD);}

104:   VecDestroy(&x);
105:   VecDestroy(&b);
106:   /* you can destroy the matrices in any order you like */
107:   MatDestroy(&A);
108:   MatDestroy(&U);
109:   MatDestroy(&V);
110:   MatDestroy(&LR);

112:   /*
113:      Always call PetscFinalize() before exiting a program.  This routine
114:        - finalizes the PETSc libraries as well as MPI
115:        - provides summary and diagnostic information if certain runtime
116:          options are chosen (e.g., -log_summary).
117:   */
118:   PetscFinalize();
119:   return 0;
120: }