xref: /petsc/src/mat/utils/convert.c (revision be1d678a52e6eff2808b2fa31ae986cdbf03c9fe)
1 #define PETSCMAT_DLL
2 
3 #include "src/mat/matimpl.h"
4 
5 #undef __FUNCT__
6 #define __FUNCT__ "MatConvert_Basic"
7 /*
8   MatConvert_Basic - Converts from any input format to another format. For
9   parallel formats, the new matrix distribution is determined by PETSc.
10 
11   Does not do preallocation so in general will be slow
12  */
13 PetscErrorCode MatConvert_Basic(Mat mat,const MatType newtype,MatReuse reuse,Mat *newmat)
14 {
15   Mat                M;
16   const PetscScalar  *vwork;
17   PetscErrorCode     ierr;
18   PetscInt           i,nz,m,n,rstart,rend,lm,ln;
19   const PetscInt     *cwork;
20 
21   PetscFunctionBegin;
22   ierr = MatGetSize(mat,&m,&n);CHKERRQ(ierr);
23   ierr = MatGetLocalSize(mat,&lm,&ln);CHKERRQ(ierr);
24 
25   if (ln == n) ln = PETSC_DECIDE; /* try to preserve column ownership */
26 
27   ierr = MatCreate(mat->comm,lm,ln,m,n,&M);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 
39   if (reuse == MAT_REUSE_MATRIX) {
40     ierr = MatHeaderReplace(mat,M);CHKERRQ(ierr);
41   } else {
42     *newmat = M;
43   }
44   PetscFunctionReturn(0);
45 }
46