Date: 2022-03-04T17:38:16+00:00

Actual source code: ex12.c

      2: static char help[] = "Reads a PETSc matrix and vector from a file; expands the matrix with the vector\n\n";

      4: /*T
      5:    Concepts: Mat^ordering a matrix - loading a binary matrix and vector;
      6:    Concepts: Mat^loading a binary matrix and vector;
      7:    Concepts: Vectors^loading a binary vector;
      8:    Concepts: PetscLog^preloading executable
      9:    Processors: 1
     10: T*/

     12: /*
     13:   Include "petscmat.h" so that we can use matrices.
     14:   automatically includes:
     15:      petscsys.h       - base PETSc routines   petscvec.h    - vectors
     16:      petscmat.h    - matrices
     17:      petscis.h     - index sets            petscviewer.h - viewers
     18: */
     19: #include <petscmat.h>

     21: /*

     23:    Adds a new column and row to the vector (the last) containing the vector
     24: */
     25: PetscErrorCode PadMatrix(Mat A,Vec v,PetscScalar c,Mat *B)
     26: {
     27:   PetscErrorCode    ierr;
     28:   PetscInt          n,i,*cnt,*indices,nc;
     29:   const PetscInt    *aj;
     30:   const PetscScalar *vv,*aa;

     33:   MatGetSize(A,&n,NULL);
     34:   VecGetArrayRead(v,&vv);
     35:   PetscMalloc1(n,&indices);
     36:   for (i=0; i<n; i++) indices[i] = i;

     38:   /* determine number of nonzeros per row in the new matrix */
     39:   PetscMalloc1(n+1,&cnt);
     40:   for (i=0; i<n; i++) {
     41:     MatGetRow(A,i,&nc,NULL,NULL);
     42:     cnt[i] = nc + (vv[i] != 0.0);
     43:     MatRestoreRow(A,i,&nc,NULL,NULL);
     44:   }
     45:   cnt[n] = 1;
     46:   for (i=0; i<n; i++) {
     47:     cnt[n] += (vv[i] != 0.0);
     48:   }
     49:   MatCreateSeqAIJ(PETSC_COMM_SELF,n+1,n+1,0,cnt,B);
     50:   MatSetOption(*B,MAT_IGNORE_ZERO_ENTRIES,PETSC_TRUE);

     52:   /* copy over the matrix entries from the matrix and then the vector */
     53:   for (i=0; i<n; i++) {
     54:     MatGetRow(A,i,&nc,&aj,&aa);
     55:     MatSetValues(*B,1,&i,nc,aj,aa,INSERT_VALUES);
     56:     MatRestoreRow(A,i,&nc,&aj,&aa);
     57:   }
     58:   MatSetValues(*B,1,&n,n,indices,vv,INSERT_VALUES);
     59:   MatSetValues(*B,n,indices,1,&n,vv,INSERT_VALUES);
     60:   MatSetValues(*B,1,&n,1,&n,&c,INSERT_VALUES);

     62:   MatAssemblyBegin(*B,MAT_FINAL_ASSEMBLY);
     63:   MatAssemblyEnd(*B,MAT_FINAL_ASSEMBLY);
     64:   VecRestoreArrayRead(v,&vv);
     65:   PetscFree(cnt);
     66:   PetscFree(indices);
     67:   return(0);
     68: }

     70: int main(int argc,char **args)
     71: {
     72:   Mat            A,B;
     73:   PetscViewer    fd;                        /* viewer */
     74:   char           file[PETSC_MAX_PATH_LEN];  /* input file name */
     76:   PetscBool      flg;
     77:   Vec            v;

     79:   PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr;
     80:   /*
     81:      Determine files from which we read the two linear systems
     82:      (matrix and right-hand-side vector).
     83:   */
     84:   PetscOptionsGetString(NULL,NULL,"-f0",file,sizeof(file),&flg);
     85:   if (!flg) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_USER,"Must indicate binary file with the -f0 option");

     87:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,file,FILE_MODE_READ,&fd);

     89:   MatCreate(PETSC_COMM_WORLD,&A);
     90:   MatSetType(A,MATSEQAIJ);
     91:   MatLoad(A,fd);
     92:   VecCreate(PETSC_COMM_WORLD,&v);
     93:   VecLoad(v,fd);
     94:   MatView(A,PETSC_VIEWER_STDOUT_SELF);
     95:   PadMatrix(A,v,3.0,&B);
     96:   MatView(B,PETSC_VIEWER_STDOUT_SELF);
     97:   MatDestroy(&B);
     98:   MatDestroy(&A);
     99:   VecDestroy(&v);
    100:   PetscViewerDestroy(&fd);

    102:   PetscFinalize();
    103:   return ierr;
    104: }

    106: /*TEST

    108:    test:
    109:       args: -f0 ${wPETSC_DIR}/share/petsc/datafiles/matrices/ns-real-int32-float64
    110:       requires: double !complex !defined(PETSC_USE_64BIT_INDICES)

    112: TEST*/