xref: /petsc/src/mat/utils/convert.c (revision b41ce5d507ea9a58bfa83cf403107a702e77a67d)
1 
2 #include <petsc/private/matimpl.h>
3 
4 /*
5   MatConvert_Basic - Converts from any input format to another format. For
6   parallel formats, the new matrix distribution is determined by PETSc.
7 
8   Does not do preallocation so in general will be slow
9  */
10 PETSC_INTERN PetscErrorCode MatConvert_Basic(Mat mat, MatType newtype,MatReuse reuse,Mat *newmat)
11 {
12   Mat               M;
13   const PetscScalar *vwork;
14   PetscErrorCode    ierr;
15   PetscInt          nz,i,m,n,rstart,rend,lm,ln;
16   const PetscInt    *cwork;
17   PetscBool         isSBAIJ;
18 
19   PetscFunctionBegin;
20   ierr = PetscObjectTypeCompare((PetscObject)mat,MATSEQSBAIJ,&isSBAIJ);CHKERRQ(ierr);
21   if (!isSBAIJ) {
22     ierr = PetscObjectTypeCompare((PetscObject)mat,MATMPISBAIJ,&isSBAIJ);CHKERRQ(ierr);
23   }
24   if (isSBAIJ) SETERRQ(PetscObjectComm((PetscObject)mat),PETSC_ERR_SUP,"Cannot convert from SBAIJ matrix since cannot obtain entire rows of matrix");
25 
26 
27   ierr = MatGetSize(mat,&m,&n);CHKERRQ(ierr);
28   ierr = MatGetLocalSize(mat,&lm,&ln);CHKERRQ(ierr);
29 
30   if (ln == n) ln = PETSC_DECIDE; /* try to preserve column ownership */
31 
32   ierr = MatCreate(PetscObjectComm((PetscObject)mat),&M);CHKERRQ(ierr);
33   ierr = MatSetSizes(M,lm,ln,m,n);CHKERRQ(ierr);
34   ierr = MatSetBlockSizesFromMats(M,mat,mat);CHKERRQ(ierr);
35   ierr = MatSetType(M,newtype);CHKERRQ(ierr);
36 
37   ierr = MatSeqDenseSetPreallocation(M,NULL);CHKERRQ(ierr);
38   ierr = MatMPIDenseSetPreallocation(M,NULL);CHKERRQ(ierr);
39   ierr = MatSetUp(M);CHKERRQ(ierr);
40   ierr = MatSetOption(M,MAT_NEW_NONZERO_LOCATION_ERR,PETSC_FALSE);CHKERRQ(ierr);
41   ierr = MatSetOption(M,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_FALSE);CHKERRQ(ierr);
42 
43     ierr = PetscObjectTypeCompare((PetscObject)M,MATSEQSBAIJ,&isSBAIJ);CHKERRQ(ierr);
44   if (!isSBAIJ) {
45     ierr = PetscObjectTypeCompare((PetscObject)M,MATMPISBAIJ,&isSBAIJ);CHKERRQ(ierr);
46   }
47   if (isSBAIJ) {
48     ierr = MatSetOption(M,MAT_IGNORE_LOWER_TRIANGULAR,PETSC_TRUE);CHKERRQ(ierr);
49   }
50 
51   ierr = MatGetOwnershipRange(mat,&rstart,&rend);CHKERRQ(ierr);
52   for (i=rstart; i<rend; i++) {
53     ierr = MatGetRow(mat,i,&nz,&cwork,&vwork);CHKERRQ(ierr);
54     ierr = MatSetValues(M,1,&i,nz,cwork,vwork,INSERT_VALUES);CHKERRQ(ierr);
55     ierr = MatRestoreRow(mat,i,&nz,&cwork,&vwork);CHKERRQ(ierr);
56   }
57   ierr = MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
58   ierr = MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
59 
60   if (reuse == MAT_INPLACE_MATRIX) {
61     ierr = MatHeaderReplace(mat,&M);CHKERRQ(ierr);
62   } else {
63     *newmat = M;
64   }
65   PetscFunctionReturn(0);
66 }
67