xref: /petsc/src/mat/utils/convert.c (revision 7d0a6c19129e7069c8a40e210b34ed62989173db)
1 
2 #include "private/matimpl.h"
3 
4 #undef __FUNCT__
5 #define __FUNCT__ "MatConvert_Basic"
6 /*
7   MatConvert_Basic - Converts from any input format to another format. For
8   parallel formats, the new matrix distribution is determined by PETSc.
9 
10   Does not do preallocation so in general will be slow
11  */
12 PetscErrorCode MatConvert_Basic(Mat mat, const MatType newtype,MatReuse reuse,Mat *newmat)
13 {
14   Mat                M;
15   const PetscScalar  *vwork;
16   PetscErrorCode     ierr;
17   PetscInt           i,nz,m,n,rstart,rend,lm,ln;
18   const PetscInt     *cwork;
19 
20   PetscFunctionBegin;
21   ierr = MatGetSize(mat,&m,&n);CHKERRQ(ierr);
22   ierr = MatGetLocalSize(mat,&lm,&ln);CHKERRQ(ierr);
23 
24   if (ln == n) ln = PETSC_DECIDE; /* try to preserve column ownership */
25 
26   ierr = MatCreate(((PetscObject)mat)->comm,&M);CHKERRQ(ierr);
27   ierr = MatSetSizes(M,lm,ln,m,n);CHKERRQ(ierr);
28   ierr = MatSetType(M,newtype);CHKERRQ(ierr);
29 
30   ierr = MatGetOwnershipRange(mat,&rstart,&rend);CHKERRQ(ierr);
31   for (i=rstart; i<rend; i++) {
32     ierr = MatGetRow(mat,i,&nz,&cwork,&vwork);CHKERRQ(ierr);
33     ierr = MatSetValues(M,1,&i,nz,cwork,vwork,INSERT_VALUES);CHKERRQ(ierr);
34     ierr = MatRestoreRow(mat,i,&nz,&cwork,&vwork);CHKERRQ(ierr);
35   }
36   ierr = MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
37   ierr = MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
38   if (mat->hermitian){
39     ierr = MatSetOption(M,MAT_HERMITIAN,PETSC_TRUE);CHKERRQ(ierr);
40   }
41 
42   if (reuse == MAT_REUSE_MATRIX) {
43     ierr = MatHeaderReplace(mat,M);CHKERRQ(ierr);
44   } else {
45     *newmat = M;
46   }
47   PetscFunctionReturn(0);
48 }
49