how to add a parallel MatMatSolve() function?

[Yujie]

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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