Thanks, Barry, I meant in ComputeRHS(KSP,Vec,void* ctx), I can only
has one ponter array like double* arr1d which can onle be casted from void *ctx
to 1d array directly. If it is a 3d array outside, I have to use 3
for-iterations to convert the 1d array ( arr1d ) to a 3d array (arr3d) inside,
like int i,j,k,cnt; cnt=0; double*
arr1d=static_cast<double *>(ctx); for (i=0; i<3; i++) { for(j=0; j<3;
j++) { for(k=0; k<3;k++) arr3d[i][j][k]=arr1d[cnt];
cnt++; } }
but cannot use the arr3d directly inside the function. Is there anyway to
cast *ctx to a 3d array directly? Thanks again.
> > int size_in_func
> > double* arr1d=static_cast<double *>(ctx);
> Subject: Re: [petsc-users] passing variables into (*func)(KSP, Vec, void*) in
> the interface of KSPSetComputeRHS
> From: [email protected]
> Date: Sun, 4 Aug 2013 17:17:59 -0500
> CC: [email protected]; [email protected]
> To: [email protected]
>
>
> Sure, just caste it to a void* and then caste it back in the subroutine.
> Note that in parallel you will only want to store on each process the "local"
> values for the field, not all the values.
>
> Barry
>
> On Aug 4, 2013, at 3:35 PM, Roc Wang <[email protected]> wrote:
>
> > Thanks a lot, Dave,
> >
> > I can pass an 1-D array into ComputeRHS via *void ctx.
> >
> > I am using the following procedure:
> >
> > in main()
> > {//-------
> > ...
> > double array_1d[array_size];
> >
> > ComputeRHS(array_1d);
> > ierr = KSPSetComputeRHS(ksp,ComputeRHS, array_1d);
> > ...
> > //--------
> > }
> >
> > in ComputeRHS(KSP,Vec,void* ctx )
> > {
> > int size_in_func
> > double* arr1d=static_cast<double *>(ctx);
> > for (i=0;i<size_in_func; i++)
> > cout<<" ComputeRHS="<<arr1d[i] <<endl;
> > }
> >
> > Definitely, a 3d array can be passed by converting it to 1d in main()
> > before calling KSPSetComputeRHS and back to 3d in ComputeRHS(). However,
> > is it possible to pass 3d array directly? Thanks.
> >
> > Date: Sun, 4 Aug 2013 18:18:54 +0200
> > Subject: Re: [petsc-users] passing variables into (*func)(KSP, Vec, void*)
> > in the interface of KSPSetComputeRHS
> > From: [email protected]
> > To: [email protected]
> > CC: [email protected]
> >
> > The last argument you give to KSPSetComputeRHS() will be passed into your
> > user defined function ComputeRHS(). All data needed to evaluate the rhs
> > should be made available through that pointer (void *ctx)
> >
> >
> > On Sunday, 4 August 2013, Roc Wang wrote:
> > Hello, I am developing a poisson solver based on the example code
> > petsc-3.4.0/src/ksp/ksp/examples/tutorials/ex45.c.
> >
> > I have a question on utilizing functions
> > KSPSetComputeRHS (KSP ksp,PetscErrorCode (*func)(KSP,Vec,void*),void *ctx)
> > and ComputeRHS(KSP,Vec,void*) which is the (*func)(KSP,Vec,void*) in the
> > interface.
> >
> >
> > Since I have source term generated on the right hand side of Poisson
> > equation and they are computed outside KSPSetComputeRHS() and ComputeRHS(),
> > an array of source term variables must be passed into ComuteRHS() function.
> > From the manual online, it seems the interface of ComputeRHS is only for
> > passing variables from inside of ComputeRHS to KSPSetComputeRHS. There is
> > not a dummy for passing into ComputeRHS. Can anybody give me suggestions on
> > it? Thanks in advance.
> >
> >
> >
>
