[petsc-users] unexpected ordering when VecSetValues set multiples values
Matteo Parsani
parsani.matteo at gmail.com
Fri Jun 7 13:20:13 CDT 2013
Hello Barry,
I have tried to follow the debugger but I got lost.
I have run my code in this way:
./NSE -start_in_debugger noxterm
then after getting some output I get
gdb()
Then I type *break vecsetvalues_
*
and a break point is generated
Breakpoint 1 at 0x2ae97eda5827: file
/scratch/home0/pmatteo/research/lib_src/petsc/src/vec/vec/interface/ftn-auto/rvectorf.c,
line 239.
I keep typing *n* and it goes on. It shows me every time vectsetvalues is
called but it never goes inside vectsetvalues.
I have tested the VecSetValues with just two elements and it does not work.
It sets correctly the values both in serial and in parallel if I set one
value at the time.
Thanks
**
On Tue, Apr 30, 2013 at 8:35 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
> On Apr 30, 2013, at 7:21 AM, Matteo Parsani <parsani.matteo at gmail.com>
> wrote:
>
> > Hello Barry,
> > it does not work also if m is not so large.
>
> Then you need to run in the debugger. You can use the command line
> options
>
> -start_in_debugger noxterm
>
> in the debugger put a break point in vecsetvalues_ (yes lower case
> followed by an underscore) then when it
> gets to that point print the size of the array and the values in the
> integer and double array to see if they match, then step into the
> VecSetValues() function that is called by vecsetvalues_() and look at the
> array values ago, continue to step along and it will go into
> VecSetValues_Seq() and start actually putting the values into the Vec array.
>
> Barry
>
> >
> > Thanks again.
> >
> >
> >
> >
> >
> >
> > On Fri, Apr 26, 2013 at 3:23 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> >
> > Shouldn't matter that it is called from Fortran we do it all the time.
> >
> > Does it work if the final m is not very large?
> >
> > You may need to run in the debugger and follow the values through the
> code to see why they don't get to where they belong.
> >
> >
> > Barry
> >
> > Could also be a buggy fortran compiler.
> >
> >
> > On Apr 26, 2013, at 2:06 PM, Matteo Parsani <parsani.matteo at gmail.com>
> wrote:
> >
> > > Hello Barry,
> > > sorry I modified few things just before to write the mail.
> > > The correct loop with the correct name of the variables is the
> following
> > >
> > > ! Number of DOFs owned by this process
> > > len_local = (elem_high-elem_low+1)*nodesperelem*nequations
> > >
> > > ! Allocate memory for x_vec_local and index_list
> > > allocate(x_vec_local(len_local))
> > > allocate(index_list(len_local))
> > >
> > >
> > > m = 1
> > > ! Loop over all elements
> > > do ielem = elem_low, elem_high
> > > ! Loop over all nodes in the element
> > > do inode = 1, nodesperelem
> > > !Loop over all equations
> > > do ieq = 1, nequations
> > > ! Add element to x_vec_local
> > > x_vec_local(m) = ug(ieq,inode,ielem)
> > > ! Add element to index list
> > > index_list(m) =
> (elem_low-1)*nodesperelem*nequations+m-1
> > > ! Update m index
> > > m = m+1
> > > end do
> > > end do
> > > end do
> > >
> > > ! HERE I HAVE PRINTED x_vec_local, ug and index_list
> > >
> > > ! Set values in the portion of the vector owned by the process
> > > call
> VecSetValues(x_vec_in,m-1,index_list,x_vec_local,INSERT_VALUES,&
> > > & ierr_local)
> > >
> > > ! Assemble initial guess
> > > call VecAssemblyBegin(x_vec_in,ierr_local)
> > > call VecAssemblyEnd(x_vec_in,ierr_local)
> > >
> > >
> > >
> > > I have printed the values and the indices I want to pass to
> VecSetValues() and they are correct.
> > >
> > > I also printed the values after VecSetValues() has been called and
> they are wrong.
> > >
> > > The attachment shows that.
> > >
> > >
> > > Could it be a problem of VecSetValues() + F90 when more than 1
> elements is set?
> > >
> > > I order to debug my the code I am running just with 1 processor. Thus
> the process owns all the DOFs.
> > >
> > > Thank you.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > On Fri, Apr 26, 2013 at 2:39 PM, Barry Smith <bsmith at mcs.anl.gov>
> wrote:
> > >
> > > On Apr 26, 2013, at 10:20 AM, Matteo Parsani <parsani.matteo at gmail.com>
> wrote:
> > >
> > > > Hello,
> > > > I have some problem when I try to set multiple values to a PETSc
> vector that I will use later on with SNES. I am using Fortran 90.
> > > > Here the problem and two fixes that however are not so good for
> performances reasons. The code is very simple.
> > > >
> > > > Standard approach that does not work correctly: (I am probably doing
> something wrong)
> > > >
> > > > m = 1
> > > > ! Loop over all elements
> > > > do ielem = elem_low, elem_high
> > > > ! Loop over all nodes in the element
> > > > do inode = 1, nodesperelem
> > > > !Loop over all equations
> > > > do ieq = 1, nequations
> > > > ! Add element to x_vec_local
> > > > x_vec_local(m) = ug(ieq,inode,ielem)
> > > > ! Add element to index list
> > > > ind(m) = (elem_low-1)*nodesperelem*nequations+m-1
> > > > ! Update m index
> > > > m = m+1
> > > > end do
> > > > end do
> > > > end do
> > > >
> > > > ! Set values in the portion of the vector owned by the process
> > > > call
> VecSetValues(x_vec_in,len_local,index_list,x_vec_local,INSERT_VALUES,&
> > >
> > > What is len_local and index_list? They do not appear in the loop
> above. Shouldn't you be passing m-1 for the length and ind for the indices?
> > >
> > > I would first print out the all the values in your input to
> VecSetValues() and make sure they are correct.
> > >
> > > Barry
> > >
> > > > & ierr_local)
> > > >
> > > > ! Assemble initial guess
> > > > call VecAssemblyBegin(x_vec_in,ierr_local)
> > > > call VecAssemblyEnd(x_vec_in,ierr_local)
> > > >
> > > > Then I print my expected values and the values contained in the
> PETSc vector to a file. See attachment. I am running in serial for the
> moment BUT strangely if you look at the file I have attached the first 79
> DOFs values have a wrong ordering and the remaining 80 are zero.
> > > >
> > > >
> > > > 1st approach: set just one value at the time inside the loop.
> > > > m = 1
> > > > ! Loop over all elements
> > > > do ielem = elem_low, elem_high
> > > > ! Loop over all nodes in the element
> > > > do inode = 1, nodesperelem
> > > > !Loop over all equations
> > > > do ieq = 1, nequations
> > > > ! Add element to x_vec_local
> > > > value = ug(ieq,inode,ielem)
> > > > ! Add element to index list
> > > > ind = (elem_low-1)*nodesperelem*nequations+m-1
> > > > call
> VecSetValues(x_vec_in,1,ind,value,INSERT_VALUES,&
> > > > & ierr_local)
> > > > ! Update m index
> > > > m = m+1
> > > > end do
> > > > end do
> > > > end do
> > > >
> > > >
> > > > This works fine. As you can see I am using the same expression used
> in the previous loop to compute the index of the element that I have to add
> in the x_vec_in, i.e.
> > > > ind = (elem_low-1)*nodesperelem*nequations+m-1
> > > >
> > > > Thus I cannot see which is the problem.
> > > >
> > > > 2nd approach: get the pointer to the local part of the global vector
> and use it to set the values in the global vector
> > > >
> > > > m = 1
> > > > ! Loop over all elements
> > > > do ielem = elem_low, elem_high
> > > > ! Loop over all nodes in the element
> > > > do inode = 1, nodesperelem
> > > > !Loop over all equations
> > > > do ieq = 1, nequations
> > > > ! Add element to x_vec_local
> > > > tmp(m) = ug(ieq,inode,ielem)
> > > > ! Update m index
> > > > m = m+1
> > > > end do
> > > > end do
> > > > end do
> > > >
> > > >
> > > > This works fine too.
> > > >
> > > >
> > > > Jut to be complete. I use the following two approaches to view the
> vector:
> > > >
> > > > call VecView(x_vec_in,PETSC_VIEWER_STDOUT_WORLD,ierr_local)
> > > >
> > > >
> > > > and
> > > >
> > > > call VecGetArrayF90(x_vec_in,tmp,ierr_local)
> > > >
> > > >
> > > > m = 1
> > > > ! Loop over all elements
> > > > do ielem = elem_low, elem_high
> > > > ! Loop over all nodes in the element
> > > > do inode = 1, nodesperelem
> > > > !Loop over all equations
> > > > do ieq = 1, nequations
> > > > write(*,*) m,index_list(m),x_vec_local(m),tmp(m)
> > > > ! Update m index
> > > > m = m+1
> > > > end do
> > > > end do
> > > > end do
> > > >
> > > >
> > > > Thank you.
> > > >
> > > >
> > > > --
> > > > Matteo
> > > > <values.txt>
> > >
> > >
> > >
> > >
> > > --
> > > Matteo
> > > <comparison.txt>
> >
> >
> >
> >
> > --
> > Matteo
>
>
--
Matteo
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