Actual source code: ex12.c

petsc-3.9.0 2018-04-07
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  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:    requires: define(PETSC_USE_REAL_DOUBLE) !define(USE_64BIT_INDICES)
 11: T*/



 15: /*
 16:   Include "petscmat.h" so that we can use matrices.
 17:   automatically includes:
 18:      petscsys.h       - base PETSc routines   petscvec.h    - vectors
 19:      petscmat.h    - matrices
 20:      petscis.h     - index sets            petscviewer.h - viewers
 21: */
 22:  #include <petscmat.h>

 24: /*

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

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

 41:   /* determine number of nonzeros per row in the new matrix */
 42:   PetscMalloc1(n+1,&cnt);
 43:   for (i=0; i<n; i++) {
 44:     MatGetRow(A,i,&nc,NULL,NULL);
 45:     cnt[i] = nc + (vv[i] != 0.0);
 46:     MatRestoreRow(A,i,&nc,NULL,NULL);
 47:   }
 48:   cnt[n] = 1;
 49:   for (i=0; i<n; i++) {
 50:     cnt[n] += (vv[i] != 0.0);
 51:   }
 52:   MatCreateSeqAIJ(PETSC_COMM_SELF,n+1,n+1,0,cnt,B);
 53:   MatSetOption(*B,MAT_IGNORE_ZERO_ENTRIES,PETSC_TRUE);

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

 65:   MatAssemblyBegin(*B,MAT_FINAL_ASSEMBLY);
 66:   MatAssemblyEnd(*B,MAT_FINAL_ASSEMBLY);
 67:   VecRestoreArrayRead(v,&vv);
 68:   PetscFree(cnt);
 69:   PetscFree(indices);
 70:   return(0);
 71: }


 74: int main(int argc,char **args)
 75: {
 76:   Mat            A,B;
 77:   PetscViewer    fd;                        /* viewer */
 78:   char           file[PETSC_MAX_PATH_LEN];  /* input file name */
 80:   PetscBool      flg;
 81:   Vec            v;

 83:   PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr;
 84:   /*
 85:      Determine files from which we read the two linear systems
 86:      (matrix and right-hand-side vector).
 87:   */
 88:   PetscOptionsGetString(NULL,NULL,"-f0",file,PETSC_MAX_PATH_LEN,&flg);
 89:   if (!flg) SETERRQ(PETSC_COMM_WORLD,1,"Must indicate binary file with the -f0 option");

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

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

106:   PetscFinalize();
107:   return ierr;
108: }



112: /*TEST

114:    test:
115:       args: -f0 ${wPETSC_DIR}/share/petsc/datafiles/matrices/ns-real-int32-float64
116:       requires: double !complex !define(PETSC_USE_64BIT_INDICES)

118: TEST*/