2: static char help[] = "Reads a PETSc matrix and vector from a file appends the vector the matrix\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>
 20: #include <../src/mat/impls/aij/seq/aij.h>

 24: PetscErrorCode PadMatrix(Mat A,Vec v,PetscScalar c,Mat *B)
 25: {
 27:   PetscInt       n    = A->rmap->n,i,*cnt,*indices;
 28:   Mat_SeqAIJ     *aij = (Mat_SeqAIJ*)A->data;
 29:   PetscScalar    *vv;

 32:   VecGetArray(v,&vv);
 33:   PetscMalloc1(n,&indices);
 34:   for (i=0; i<n; i++) indices[i] = i;

 36:   /* determine number of nonzeros per row in the new matrix */
 37:   PetscMalloc1(n+1,&cnt);
 38:   for (i=0; i<n; i++) {
 39:     cnt[i] = aij->i[i+1] - aij->i[i] + (vv[i] != 0.0);
 40:   }
 41:   cnt[n] = 1;
 42:   for (i=0; i<n; i++) {
 43:     cnt[n] += (vv[i] != 0.0);
 44:   }
 45:   MatCreateSeqAIJ(PETSC_COMM_SELF,n+1,n+1,0,cnt,B);
 46:   MatSetOption(*B,MAT_IGNORE_ZERO_ENTRIES,PETSC_TRUE);

 48:   /* copy over the matrix entries from the matrix and then the vector */
 49:   for (i=0; i<n; i++) {
 50:     MatSetValues(*B,1,&i,aij->i[i+1] - aij->i[i],aij->j + aij->i[i],aij->a + aij->i[i],INSERT_VALUES);
 51:   }
 52:   MatSetValues(*B,1,&n,n,indices,vv,INSERT_VALUES);
 53:   MatSetValues(*B,n,indices,1,&n,vv,INSERT_VALUES);
 54:   MatSetValues(*B,1,&n,1,&n,&c,INSERT_VALUES);

 56:   MatAssemblyBegin(*B,MAT_FINAL_ASSEMBLY);
 57:   MatAssemblyEnd(*B,MAT_FINAL_ASSEMBLY);
 58:   VecRestoreArray(v,&vv);
 59:   PetscFree(cnt);
 60:   PetscFree(indices);
 61:   return(0);
 62: }


 67: int main(int argc,char **args)
 68: {
 69:   Mat            A,B;
 70:   PetscViewer    fd;                        /* viewer */
 71:   char           file[PETSC_MAX_PATH_LEN];  /* input file name */
 73:   PetscBool      flg;
 74:   Vec            v;

 76:   PetscInitialize(&argc,&args,(char*)0,help);


 79:   /*
 80:      Determine files from which we read the two linear systems
 81:      (matrix and right-hand-side vector).
 82:   */
 83:   PetscOptionsGetString(NULL,NULL,"-f0",file,PETSC_MAX_PATH_LEN,&flg);
 84:   if (!flg) SETERRQ(PETSC_COMM_WORLD,1,"Must indicate binary file with the -f0 option");

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

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

 99:   PetscFinalize();
100:   return 0;
101: }