how to add a parallel MatMatSolve() function?
Yujie
recrusader at gmail.com
Fri Feb 29 21:59:48 CST 2008
Thanks a lot:).
Regards,
Yujie
On 3/1/08, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>
> The code I provided works for any LU solver; the way the PETSc code is
> written you can customizea routine for any specific matrix format, like
> the PETSc SuperLU_Dist format. You are certainly
> free to try to write a custom one for SuperLU_dist() (see
> MatMatSolve_SeqAIJ() for how to do this).
> It is your time, not mine. Personally I'd rather have the computer run a
> few more minutes then spend
> my time looking at code :-)
>
> Barry
>
> On Feb 29, 2008, at 9:35 PM, Yujie wrote:
>
> Dear Barry:
>
> I have checked SuperLU_Dist codes. It looks like relative easy to write
> codes for AX=B based on MatSolve(). This is why I ask you the above problem.
>
> how about your advice?
> thanks a lot.
>
> Regards,
> Yujie
>
> On 3/1/08, Barry Smith <bsmith at mcs.anl.gov> wrote:
> >
> >
> > Some direct solver packages have support for solving directly with
> > several right hand sides at the same time.They could be a bit faster
> > than solving one at a time; maybe 30% faster at most, not 10 times faster.
> > What is more
> > important solving the problem you want to solve in a reasonable time or
> > solving the problem a bit faster
> > after spending several weeks writing the much more complicated code?
> >
> > Barry
> >
> > On Feb 29, 2008, at 8:01 PM, Yujie wrote:
> >
> > Dear Barry:
> >
> > Thank you for your help. I check the codes
> > roughly, the method in the codes is to use MatSolve() to solve AX=B in a loop. I also consider such a method.
> > However, I am wondering whether it is slower than the method that
> > directly solves AX=B? thanks again.
> >
> > Regards,
> > Yujie
> >
> > On 2/29/08, Barry Smith <bsmith at mcs.anl.gov> wrote:
> > >
> > >
> > > Please edit the file src/mat/interface/matrix.c and remove the
> > > function MatMatSolve(). Replace it with the following two functions,
> > > then run "make lib shared" in that directory. Please let us know at
> > > petsc-maint at mcs.anl.gov
> > > if it crashes or produces incorrect
> > > results.
> > >
> > > Barry
> > >
> > >
> > >
> > > #undef __FUNCT__
> > > #define __FUNCT__ "MatMatSolve_Basic"
> > > PetscErrorCode PETSCMAT_DLLEXPORT MatMatSolve_Basic(Mat A,Mat B,Mat X)
> > > {
> > > PetscErrorCode ierr;
> > > Vec b,x;
> > > PetscInt m,N,i;
> > > PetscScalar *bb,*xx;
> > >
> > > PetscFunctionBegin;
> > > ierr = MatGetArray(B,&bb);CHKERRQ(ierr);
> > > ierr = MatGetArray(X,&xx);CHKERRQ(ierr);
> > > ierr = MatGetLocalSize(B,&m,PETSC_NULL);CHKERRQ(ierr); /* number
> > > local rows */
> > > ierr = MatGetSize(B,PETSC_NULL,&N);CHKERRQ(ierr); /* total
> > > columns in dense matrix */
> > > ierr = VecCreateMPIWithArray(A-
> > > >hdr.comm,m,PETSC_DETERMINE,PETSC_NULL,&b);CHKERRQ(ierr);
> > > ierr = VecCreateMPIWithArray(A-
> > > >hdr.comm,m,PETSC_DETERMINE,PETSC_NULL,&x);CHKERRQ(ierr);
> > > for (i=0; i<N; i++) {
> > > ierr = VecPlaceArray(b,bb + i*m);CHKERRQ(ierr);
> > > ierr = VecPlaceArray(x,xx + i*m);CHKERRQ(ierr);
> > > ierr = MatSolve(A,b,x);CHKERRQ(ierr);
> > > }
> > > ierr = VecDestroy(b);CHKERRQ(ierr);
> > > ierr = VecDestroy(x);CHKERRQ(ierr);
> > > PetscFunctionReturn(0);
> > > }
> > >
> > > #undef __FUNCT__
> > > #define __FUNCT__ "MatMatSolve"
> > > /*@
> > > MatMatSolve - Solves A X = B, given a factored matrix.
> > >
> > > Collective on Mat
> > >
> > > Input Parameters:
> > > + mat - the factored matrix
> > > - B - the right-hand-side matrix (dense matrix)
> > >
> > > Output Parameter:
> > > . B - the result matrix (dense matrix)
> > >
> > > Notes:
> > > The matrices b and x cannot be the same. I.e., one cannot
> > > call MatMatSolve(A,x,x).
> > >
> > > Notes:
> > > Most users should usually employ the simplified KSP interface for
> > > linear solvers
> > > instead of working directly with matrix algebra routines such as
> > > this.
> > > See, e.g., KSPCreate(). However KSP can only solve for one vector
> > > (column of X)
> > > at a time.
> > >
> > > Level: developer
> > >
> > > Concepts: matrices^triangular solves
> > >
> > > .seealso: MatMatSolveAdd(), MatMatSolveTranspose(),
> > > MatMatSolveTransposeAdd(), MatLUFactor(), MatCholeskyFactor()
> > > @*/
> > > PetscErrorCode PETSCMAT_DLLEXPORT MatMatSolve(Mat A,Mat B,Mat X)
> > > {
> > > PetscErrorCode ierr;
> > >
> > > PetscFunctionBegin;
> > > PetscValidHeaderSpecific(A,MAT_COOKIE,1);
> > > PetscValidType(A,1);
> > > PetscValidHeaderSpecific(B,MAT_COOKIE,2);
> > > PetscValidHeaderSpecific(X,MAT_COOKIE,3);
> > > PetscCheckSameComm(A,1,B,2);
> > > PetscCheckSameComm(A,1,X,3);
> > > if (X == B) SETERRQ(PETSC_ERR_ARG_IDN,"X and B must be different
> > > matrices");
> > > if (!A->factor) SETERRQ(PETSC_ERR_ARG_WRONGSTATE,"Unfactored
> > > matrix");
> > > if (A->cmap.N != X->rmap.N) SETERRQ2(PETSC_ERR_ARG_SIZ,"Mat A,Mat
> > > X: global dim %D %D",A->cmap.N,X->rmap.N);
> > > if (A->rmap.N != B->rmap.N) SETERRQ2(PETSC_ERR_ARG_SIZ,"Mat A,Mat
> > > B: global dim %D %D",A->rmap.N,B->rmap.N);
> > > if (A->rmap.n != B->rmap.n) SETERRQ2(PETSC_ERR_ARG_SIZ,"Mat A,Mat
> > > B: local dim %D %D",A->rmap.n,B->rmap.n);
> > > if (!A->rmap.N && !A->cmap.N) PetscFunctionReturn(0);
> > > ierr = MatPreallocated(A);CHKERRQ(ierr);
> > >
> > > ierr = PetscLogEventBegin(MAT_MatSolve,A,B,X,0);CHKERRQ(ierr);
> > > if (!A->ops->matsolve) {
> > > ierr = PetscInfo1(A,"Mat type %s using basic MatMatSolve",
> > > ((PetscObject)A)->type_name);CHKERRQ(ierr);
> > > ierr = MatMatSolve_Basic(A,B,X);CHKERRQ(ierr);
> > > } else {
> > > ierr = (*A->ops->matsolve)(A,B,X);CHKERRQ(ierr);
> > > }
> > > ierr = PetscLogEventEnd(MAT_MatSolve,A,B,X,0);CHKERRQ(ierr);
> > > ierr = PetscObjectStateIncrease((PetscObject)X);CHKERRQ(ierr);
> > > PetscFunctionReturn(0);
> > >
> > > }
> > >
> > > On Feb 29, 2008, at 6:46 PM, Yujie wrote:
> > >
> > > > Hi, everyone
> > > >
> > > > I am considering to add a parallel MatMatSolve() into PETSc based on
> > > > SuperLu_DIST or Spooles. If I want to use it like current sequential
> > > > MatMatSolve() in the application codes, how to do it? Could you give
> > > > me some examples about how to add a new function?
> > > > thanks a lot.
> > > >
> > > > Regards,
> > > > Yujie
> > >
> > >
> >
> >
>
>
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