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<div class="moz-cite-prefix">Thank you so much this helps a lot with
my research. I hope that you can reuse that little example code
for some documentation on DMShell. The features available thru
that object are really good, it is just a little hard (at least
for me) to work around all the functions call to set it up.<br>
<br>
For instance I understand that the DM can be used in the KSP to
work on the Kmat operator but what is the purpose of the PCSetDM?
Using the DM on the preconditioner operator passed to the KSP?<br>
<br>
Thanks again for your help, I will try to transfer this to
FORTRAN!<br>
<br>
Cheers!<br>
<pre class="moz-signature" cols="72">Best,
Luc</pre>
On 01/30/2014 08:52 AM, Matthew Knepley wrote:<br>
</div>
<blockquote
cite="mid:CAMYG4G=8HRMmWczUq0VG=xuEk2o94LFc5_t-aQ9fmTgkrW8E4w@mail.gmail.com"
type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">On Wed, Jan 29, 2014 at 7:19 PM, Luc
Berger-Vergiat <span dir="ltr"><<a
moz-do-not-send="true" href="mailto:lb2653@columbia.edu"
target="_blank">lb2653@columbia.edu</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div>Hi Matt,<br>
I thought I would spend the time writing a small c
example of what I am doing in my FORTRAN code so that
you can more easily see what it is I am doing wrong.<br>
<br>
I attached the code and its makefile. I run the code
the following arguments:<br>
<br>
-ksp_type gmres -pc_type fieldsplit
-fieldsplit_0_pc_type ilu -fieldsplit_0_ksp_type
preonly -fieldsplit_1_pc_type jacobi
-fieldsplit_1_ksp_type preonly -ksp_view -ksp_monitor<br>
</div>
</div>
</blockquote>
<div><br>
</div>
<div>1) You need to also call PetscSectionSetDof() in order
to get full sizes. I don't just add up the fields.</div>
<div><br>
</div>
<div>2) You need to set the DM into the KSP using KSPSetDM()</div>
<div><br>
</div>
<div>3) You need to make the DM inactive if you want to
provide your own Mat/Vec using KSPSetDMActive()</div>
<div><br>
</div>
<div>
4) Then you can get rid of the special code for FS</div>
<div><br>
</div>
<div>5) Your options were wrong because you named the fields</div>
<div><br>
</div>
<div>I include a revised code sample, and you should run
with</div>
<div>
<br>
</div>
<div> -ksp_type gmres -pc_type fieldsplit
-fieldsplit_Field_0_pc_type ilu
-fieldsplit_Field_0_ksp_type preonly
-fieldsplit_Field_1_pc_type jacobi
-fieldsplit_Field_1_ksp_type preonly -ksp_view
-ksp_monitor</div>
<div><br>
</div>
<div> Thanks,</div>
<div><br>
</div>
<div> Matt</div>
<div><br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div> and get the following output:<br>
<br>
start=1, End=9.<br>
PetscSection with 2 fields<br>
field 0 with 1 components<br>
Process 0:<br>
( 1) dim 1 offset 0<br>
( 2) dim 1 offset 0<br>
( 3) dim 1 offset 0<br>
( 4) dim 1 offset 0<br>
( 5) dim 0 offset 0<br>
( 6) dim 0 offset 0<br>
( 7) dim 0 offset 0<br>
( 8) dim 0 offset 0<br>
field 1 with 1 components<br>
Process 0:<br>
( 1) dim 0 offset 1<br>
( 2) dim 0 offset 1<br>
( 3) dim 0 offset 1<br>
( 4) dim 0 offset 1<br>
( 5) dim 1 offset 0<br>
( 6) dim 1 offset 0<br>
( 7) dim 1 offset 0<br>
( 8) dim 1 offset 0<br>
PC flag for GetDMSplits: true<br>
0 KSP Residual norm 0.000000000000e+00 <br>
KSP Object: 1 MPI processes<br>
type: gmres<br>
GMRES: restart=30, using Classical (unmodified)
Gram-Schmidt Orthogonalization with no iterative
refinement<br>
GMRES: happy breakdown tolerance 1e-30<br>
maximum iterations=10000, initial guess is zero<br>
tolerances: relative=1e-05, absolute=1e-50,
divergence=10000<br>
left preconditioning<br>
using PRECONDITIONED norm type for convergence test<br>
PC Object: 1 MPI processes<br>
type: fieldsplit<br>
FieldSplit with MULTIPLICATIVE composition: total
splits = 2<br>
Solver info for each split is in the following KSP
objects:<br>
Split number 0 Defined by IS<br>
KSP Object: (fieldsplit_Field_0_) 1 MPI
processes<br>
type: preonly<br>
maximum iterations=10000, initial guess is zero<br>
tolerances: relative=1e-05, absolute=1e-50,
divergence=10000<br>
left preconditioning<br>
using NONE norm type for convergence test<br>
PC Object: (fieldsplit_Field_0_) 1 MPI
processes<br>
type: ilu<br>
ILU: out-of-place factorization<br>
0 levels of fill<br>
tolerance for zero pivot 2.22045e-14<br>
using diagonal shift on blocks to prevent zero
pivot<br>
matrix ordering: natural<br>
factor fill ratio given 1, needed 1<br>
Factored matrix follows:<br>
Matrix Object: 1 MPI processes<br>
type: seqaij<br>
rows=0, cols=0<br>
package used to perform factorization:
petsc<br>
total: nonzeros=0, allocated nonzeros=0<br>
total number of mallocs used during
MatSetValues calls =0<br>
not using I-node routines<br>
linear system matrix = precond matrix:<br>
Matrix Object: 1 MPI processes<br>
type: seqaij<br>
rows=0, cols=0<br>
total: nonzeros=0, allocated nonzeros=0<br>
total number of mallocs used during
MatSetValues calls =0<br>
not using I-node routines<br>
Split number 1 Defined by IS<br>
KSP Object: (fieldsplit_Field_1_) 1 MPI
processes<br>
type: preonly<br>
maximum iterations=10000, initial guess is zero<br>
tolerances: relative=1e-05, absolute=1e-50,
divergence=10000<br>
left preconditioning<br>
using NONE norm type for convergence test<br>
PC Object: (fieldsplit_Field_1_) 1 MPI
processes<br>
type: ilu<br>
ILU: out-of-place factorization<br>
0 levels of fill<br>
tolerance for zero pivot 2.22045e-14<br>
using diagonal shift on blocks to prevent zero
pivot<br>
matrix ordering: natural<br>
factor fill ratio given 1, needed 1<br>
Factored matrix follows:<br>
Matrix Object: 1 MPI processes<br>
type: seqaij<br>
rows=0, cols=0<br>
package used to perform factorization:
petsc<br>
total: nonzeros=0, allocated nonzeros=0<br>
total number of mallocs used during
MatSetValues calls =0<br>
not using I-node routines<br>
linear system matrix = precond matrix:<br>
Matrix Object: 1 MPI processes<br>
type: seqaij<br>
rows=0, cols=0<br>
total: nonzeros=0, allocated nonzeros=0<br>
total number of mallocs used during
MatSetValues calls =0<br>
not using I-node routines<br>
linear system matrix = precond matrix:<br>
Matrix Object: 1 MPI processes<br>
type: seqaij<br>
rows=8, cols=8<br>
total: nonzeros=64, allocated nonzeros=160<br>
total number of mallocs used during MatSetValues
calls =8<br>
using I-node routines: found 2 nodes, limit used
is 5<br>
The solution to this problem is:<br>
Vector Object: 1 MPI processes<br>
type: seq<br>
0<br>
0<br>
0<br>
0<br>
0<br>
0<br>
0<br>
0<br>
WARNING! There are options you set that were not used!<br>
WARNING! could be spelling mistake, etc!<br>
Option left: name:-fieldsplit_0_ksp_type value:
preonly<br>
Option left: name:-fieldsplit_0_pc_type value: ilu<br>
Option left: name:-fieldsplit_1_ksp_type value:
preonly<br>
Option left: name:-fieldsplit_1_pc_type value: jacobi<br>
<br>
when I run it with the more simple arguements:<br>
<br>
-ksp_type gmres -pc_type jacobi -ksp_view -ksp_monitor<br>
<br>
I get the following output:<br>
<br>
start=1, End=9.<br>
PetscSection with 2 fields<br>
field 0 with 1 components<br>
Process 0:<br>
( 1) dim 1 offset 0<br>
( 2) dim 1 offset 0<br>
( 3) dim 1 offset 0<br>
( 4) dim 1 offset 0<br>
( 5) dim 0 offset 0<br>
( 6) dim 0 offset 0<br>
( 7) dim 0 offset 0<br>
( 8) dim 0 offset 0<br>
field 1 with 1 components<br>
Process 0:<br>
( 1) dim 0 offset 1<br>
( 2) dim 0 offset 1<br>
( 3) dim 0 offset 1<br>
( 4) dim 0 offset 1<br>
( 5) dim 1 offset 0<br>
( 6) dim 1 offset 0<br>
( 7) dim 1 offset 0<br>
( 8) dim 1 offset 0<br>
0 KSP Residual norm 4.759858191165e+00 <br>
1 KSP Residual norm 2.344421567248e+00 <br>
2 KSP Residual norm 3.208390394507e-01 <br>
3 KSP Residual norm 7.171256210359e-02 <br>
4 KSP Residual norm 1.301032901980e-02 <br>
5 KSP Residual norm 1.104121978197e-15 <br>
KSP Object: 1 MPI processes<br>
type: gmres<br>
GMRES: restart=30, using Classical (unmodified)
Gram-Schmidt Orthogonalization with no iterative
refinement<br>
GMRES: happy breakdown tolerance 1e-30<br>
maximum iterations=10000, initial guess is zero<br>
tolerances: relative=1e-05, absolute=1e-50,
divergence=10000<br>
left preconditioning<br>
using PRECONDITIONED norm type for convergence test<br>
PC Object: 1 MPI processes<br>
type: jacobi<br>
linear system matrix = precond matrix:<br>
Matrix Object: 1 MPI processes<br>
type: seqaij<br>
rows=8, cols=8<br>
total: nonzeros=64, allocated nonzeros=160<br>
total number of mallocs used during MatSetValues
calls =8<br>
using I-node routines: found 2 nodes, limit used
is 5<br>
The solution to this problem is:<br>
Vector Object: 1 MPI processes<br>
type: seq<br>
-0.977778<br>
-0.0444444<br>
-0.844444<br>
-0.327778<br>
3<br>
1<br>
1.5<br>
3<br>
<br>
It is obvious that something goes wrong in the
fieldsplit, I'm just clueless to what it is. I think
that everything is setup correctly but I'm missing
something to get the KSP to recognize my splits...<br>
<br>
Thanks for your help.<br>
<pre cols="72">Best,
Luc</pre>
On 01/28/2014 11:20 AM, Matthew Knepley wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">On Tue, Jan 28, 2014 at
10:11 AM, Luc Berger-Vergiat <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:lb2653@columbia.edu"
target="_blank">lb2653@columbia.edu</a>></span>
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div>What I don't really understand is why
the size of all the sub fields is zero?<br>
As you can see all the matrix object in my
fieldsplit preconditioner have
total:nonzeros=0, allocated nonzeros=0.<br>
<br>
This seems strange since I issued the
following command:<br>
<em></em>call
DMSetDefaultSection(FSDM, FSSection, ierr)<br>
</div>
</div>
</blockquote>
<div><br>
</div>
<div>That section looks like you never called
PetscSectionSetUp().</div>
<div><br>
</div>
<div> Matt</div>
<div> </div>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div> with a the following FSSection:<br>
PetscSection with 4 fields<br>
field 0 with 1 components<br>
Process 0:<br>
( 0) dim 0 offset 0<br>
( 1) dim 1 offset 0<br>
( 2) dim 0 offset 0<br>
( 3) dim 0 offset 0<br>
( 4) dim 1 offset 0<br>
( 5) dim 0 offset 0<br>
( 6) dim 0 offset 0<br>
( 7) dim 0 offset 0<br>
( 8) dim 0 offset 0<br>
( 9) dim 0 offset 0<br>
( 10) dim 0 offset 0<br>
( 11) dim 0 offset 0<br>
( 12) dim 0 offset 0<br>
( 13) dim 0 offset 0<br>
( 14) dim 0 offset 0<br>
( 15) dim 0 offset 0<br>
field 1 with 1 components<br>
Process 0:<br>
( 0) dim 1 offset 0<br>
( 1) dim 0 offset 1<br>
( 2) dim 1 offset 0<br>
( 3) dim 1 offset 0<br>
( 4) dim 0 offset 1<br>
( 5) dim 1 offset 0<br>
( 6) dim 0 offset 0<br>
( 7) dim 0 offset 0<br>
( 8) dim 0 offset 0<br>
( 9) dim 0 offset 0<br>
( 10) dim 0 offset 0<br>
( 11) dim 0 offset 0<br>
( 12) dim 0 offset 0<br>
( 13) dim 0 offset 0<br>
( 14) dim 0 offset 0<br>
( 15) dim 0 offset 0<br>
field 2 with 1 components<br>
Process 0:<br>
( 0) dim 0 offset 1<br>
( 1) dim 0 offset 1<br>
( 2) dim 0 offset 1<br>
( 3) dim 0 offset 1<br>
( 4) dim 0 offset 1<br>
( 5) dim 0 offset 1<br>
( 6) dim 1 offset 0<br>
( 7) dim 1 offset 0<br>
( 8) dim 1 offset 0<br>
( 9) dim 1 offset 0<br>
( 10) dim 1 offset 0<br>
( 11) dim 1 offset 0<br>
( 12) dim 0 offset 0<br>
( 13) dim 0 offset 0<br>
( 14) dim 0 offset 0<br>
( 15) dim 0 offset 0<br>
field 3 with 1 components<br>
Process 0:<br>
( 0) dim 0 offset 1<br>
( 1) dim 0 offset 1<br>
( 2) dim 0 offset 1<br>
( 3) dim 0 offset 1<br>
( 4) dim 0 offset 1<br>
( 5) dim 0 offset 1<br>
( 6) dim 0 offset 1<br>
( 7) dim 0 offset 1<br>
( 8) dim 0 offset 1<br>
( 9) dim 0 offset 1<br>
( 10) dim 0 offset 1<br>
( 11) dim 0 offset 1<br>
( 12) dim 1 offset 0<br>
( 13) dim 1 offset 0<br>
( 14) dim 1 offset 0<br>
( 15) dim 1 offset 0<br>
<br>
I thought that by using
DMSetDefaultSection() I would be done
setting the fields and that the fieldsplit
would detect that section and use it to
construct the splits.<br>
<br>
Should I use another command to tell the
PC to use the DM section?<br>
<pre cols="72">Best,
Luc</pre>
On 01/28/2014 10:25 AM, Matthew Knepley
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">On Mon, Jan
27, 2014 at 1:35 PM, Luc
Berger-Vergiat <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:lb2653@columbia.edu"
target="_blank">lb2653@columbia.edu</a>></span>
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div bgcolor="#FFFFFF"
text="#000000">
<div>Thanks Matt,<br>
this indeed setting the number
of fields earlier solve my
issue!<br>
<br>
I have now made some progress
getting my DM setup but I am
having troubles setting my
splitfield options.<br>
I ran my problem with the
-ksp_view option to see what
is going on and I guess that
somehow the section that I
define in my DM is not used by
the preconditioner to split
the fields.<br>
Here is the output of PETSc<br>
<br>
<font face="Helvetica, Arial,
sans-serif">KSP Object: 1
MPI processes<br>
type: gmres<br>
GMRES: restart=30, using
Classical (unmodified)
Gram-Schmidt
Orthogonalization with no
iterative refinement<br>
GMRES: happy breakdown
tolerance 1e-30<br>
maximum iterations=10000,
initial guess is zero<br>
tolerances:
relative=1e-08,
absolute=1e-16,
divergence=1e+16<br>
left preconditioning<br>
using PRECONDITIONED norm
type for convergence test<br>
PC Object: 1 MPI processes<br>
type: fieldsplit<br>
FieldSplit with
MULTIPLICATIVE composition:
total splits = 4<br>
Solver info for each
split is in the following
KSP objects:<br>
Split number 0 Defined
by IS<br>
</font></div>
</div>
</blockquote>
<div><br>
</div>
<div>There are 4 splits here and
they are defined by an IS. Why do
you think that is not what you
asked for?</div>
<div><br>
</div>
<div> Thanks,</div>
<div><br>
</div>
<div> Matt</div>
<div> </div>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div bgcolor="#FFFFFF"
text="#000000">
<div><font face="Helvetica,
Arial, sans-serif"> KSP
Object:
(fieldsplit_Field_0_) 1
MPI processes<br>
type: preonly<br>
maximum
iterations=10000, initial
guess is zero<br>
tolerances:
relative=1e-05,
absolute=1e-50,
divergence=10000<br>
left preconditioning<br>
using NONE norm type
for convergence test<br>
PC Object:
(fieldsplit_Field_0_) 1
MPI processes<br>
type: ilu<br>
ILU: out-of-place
factorization<br>
0 levels of fill<br>
tolerance for zero
pivot 2.22045e-14<br>
using diagonal shift
on blocks to prevent zero
pivot<br>
matrix ordering:
natural<br>
factor fill ratio
given 1, needed 1<br>
Factored matrix
follows:<br>
Matrix
Object: 1 MPI
processes<br>
type: seqaij<br>
rows=0, cols=0<br>
package used
to perform factorization:
petsc<br>
total:
nonzeros=0, allocated
nonzeros=0<br>
total number
of mallocs used during
MatSetValues calls =0<br>
not using
I-node routines<br>
linear system matrix =
precond matrix:<br>
Matrix Object: 1
MPI processes<br>
type: seqaij<br>
rows=0, cols=0<br>
total: nonzeros=0,
allocated nonzeros=0<br>
total number of
mallocs used during
MatSetValues calls =0<br>
not using I-node
routines<br>
Split number 1 Defined
by IS<br>
KSP Object:
(fieldsplit_Field_1_) 1
MPI processes<br>
type: preonly<br>
maximum
iterations=10000, initial
guess is zero<br>
tolerances:
relative=1e-05,
absolute=1e-50,
divergence=10000<br>
left preconditioning<br>
using NONE norm type
for convergence test<br>
PC Object:
(fieldsplit_Field_1_) 1
MPI processes<br>
type: ilu<br>
ILU: out-of-place
factorization<br>
0 levels of fill<br>
tolerance for zero
pivot 2.22045e-14<br>
using diagonal shift
on blocks to prevent zero
pivot<br>
matrix ordering:
natural<br>
factor fill ratio
given 1, needed 1<br>
Factored matrix
follows:<br>
Matrix
Object: 1 MPI
processes<br>
type: seqaij<br>
rows=0, cols=0<br>
package used
to perform factorization:
petsc<br>
total:
nonzeros=0, allocated
nonzeros=0<br>
total number
of mallocs used during
MatSetValues calls =0<br>
not using
I-node routines<br>
linear system matrix =
precond matrix:<br>
Matrix Object: 1
MPI processes<br>
type: seqaij<br>
rows=0, cols=0<br>
total: nonzeros=0,
allocated nonzeros=0<br>
total number of
mallocs used during
MatSetValues calls =0<br>
not using I-node
routines<br>
Split number 2 Defined
by IS<br>
KSP Object:
(fieldsplit_Field_2_) 1
MPI processes<br>
type: preonly<br>
maximum
iterations=10000, initial
guess is zero<br>
tolerances:
relative=1e-05,
absolute=1e-50,
divergence=10000<br>
left preconditioning<br>
using NONE norm type
for convergence test<br>
PC Object:
(fieldsplit_Field_2_) 1
MPI processes<br>
type: ilu<br>
ILU: out-of-place
factorization<br>
0 levels of fill<br>
tolerance for zero
pivot 2.22045e-14<br>
using diagonal shift
on blocks to prevent zero
pivot<br>
matrix ordering:
natural<br>
factor fill ratio
given 1, needed 1<br>
Factored matrix
follows:<br>
Matrix
Object: 1 MPI
processes<br>
type: seqaij<br>
rows=0, cols=0<br>
package used
to perform factorization:
petsc<br>
total:
nonzeros=0, allocated
nonzeros=0<br>
total number
of mallocs used during
MatSetValues calls =0<br>
not using
I-node routines<br>
linear system matrix =
precond matrix:<br>
Matrix Object: 1
MPI processes<br>
type: seqaij<br>
rows=0, cols=0<br>
total: nonzeros=0,
allocated nonzeros=0<br>
total number of
mallocs used during
MatSetValues calls =0<br>
not using I-node
routines<br>
Split number 3 Defined
by IS<br>
KSP Object:
(fieldsplit_Field_3_) 1
MPI processes<br>
type: preonly<br>
maximum
iterations=10000, initial
guess is zero<br>
tolerances:
relative=1e-05,
absolute=1e-50,
divergence=10000<br>
left preconditioning<br>
using NONE norm type
for convergence test<br>
PC Object:
(fieldsplit_Field_3_) 1
MPI processes<br>
type: ilu<br>
ILU: out-of-place
factorization<br>
0 levels of fill<br>
tolerance for zero
pivot 2.22045e-14<br>
using diagonal shift
on blocks to prevent zero
pivot<br>
matrix ordering:
natural<br>
factor fill ratio
given 1, needed 1<br>
Factored matrix
follows:<br>
Matrix
Object: 1 MPI
processes<br>
type: seqaij<br>
rows=0, cols=0<br>
package used
to perform factorization:
petsc<br>
total:
nonzeros=0, allocated
nonzeros=0<br>
total number
of mallocs used during
MatSetValues calls =0<br>
not using
I-node routines<br>
linear system matrix =
precond matrix:<br>
Matrix Object: 1
MPI processes<br>
type: seqaij<br>
rows=0, cols=0<br>
total: nonzeros=0,
allocated nonzeros=0<br>
total number of
mallocs used during
MatSetValues calls =0<br>
not using I-node
routines<br>
linear system matrix =
precond matrix:<br>
Matrix Object: 1 MPI
processes<br>
type: seqaij<br>
rows=16, cols=16<br>
total: nonzeros=256,
allocated nonzeros=256<br>
total number of mallocs
used during MatSetValues
calls =0<br>
using I-node routines:
found 4 nodes, limit used is
5</font><br>
<br>
I am also attaching part of my
code which I use to generate
the DM, the KSP and the PC
objects.<br>
<pre cols="72">Best,
Luc</pre>
On 01/25/2014 10:31 AM,
Matthew Knepley wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">On
Fri, Jan 24, 2014 at
5:10 PM, Luc
Berger-Vergiat <span
dir="ltr"><<a
moz-do-not-send="true"
href="mailto:lb2653@columbia.edu" target="_blank">lb2653@columbia.edu</a>></span>
wrote:<br>
<blockquote
class="gmail_quote"
style="margin:0px 0px
0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">Hi
all,<br>
I want to use PETSc as
a solver for an FEM
problem: modelization
of shear bands using a
4 fields mixed
formulation.<br>
<br>
So far I am just
trying to set up a two
fields in a Petsc
section, assign dof
too each field and
then set up the
section to pass it to
a DM. I am taking this
approach because in
general I want for
fieldsplit to work
purely on the
algebraic level
without knowledge of
boundary conditions or
geometry.<br>
<br>
As of now I have
issues when I try to
assign a point and its
associated degree of
freedom to a field
using:
PetscSectionSetFieldDof.<br>
Is this the correct
way to associate a
dof/point to a field?<br>
</blockquote>
<div><br>
</div>
<div>You have to set the
number of fields
before the chart. I am
updating the docs.</div>
<div><br>
</div>
<div> Thanks,</div>
<div> <br>
</div>
<div> Matt</div>
<div> </div>
<blockquote
class="gmail_quote"
style="margin:0px 0px
0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
I attached an example
code and its makefile.<span><font
color="#888888"><span><font
color="#888888"><br>
<br>
-- <br>
Best,<br>
Luc<br>
<br>
</font></span></font></span></blockquote>
<span><font
color="#888888"> </font></span></div>
<span><font
color="#888888"> <br>
<br clear="all">
<span><font
color="#888888">
<div><br>
</div>
-- <br>
What most
experimenters take
for granted before
they begin their
experiments is
infinitely more
interesting than
any results to
which their
experiments lead.<br>
-- Norbert Wiener
</font></span></font></span></div>
<span><font color="#888888">
</font></span></div>
<span><font color="#888888"> </font></span></blockquote>
<span><font color="#888888"> <br>
</font></span></div>
<span><font color="#888888"> </font></span></blockquote>
<span><font color="#888888"> </font></span></div>
<span><font color="#888888"> <br>
<br clear="all">
<span class=""><font
color="#888888">
<div><br>
</div>
-- <br>
What most experimenters take
for granted before they begin
their experiments is
infinitely more interesting
than any results to which
their experiments lead.<br>
-- Norbert Wiener </font></span></font></span></div>
<span class=""><font color="#888888"> </font></span></div>
<span class=""><font color="#888888"> </font></span></blockquote>
<span class=""><font color="#888888"> <br>
</font></span></div>
<span class=""><font color="#888888"> </font></span></blockquote>
<span class=""><font color="#888888"> </font></span></div>
<span class=""><font color="#888888"> <br>
<br clear="all">
<div><br>
</div>
-- <br>
What most experimenters take for granted
before they begin their experiments is
infinitely more interesting than any results
to which their experiments lead.<br>
-- Norbert Wiener </font></span></div>
</div>
</blockquote>
<br>
</div>
</blockquote>
</div>
<br>
<br clear="all">
<div><br>
</div>
-- <br>
What most experimenters take for granted before they begin
their experiments is infinitely more interesting than any
results to which their experiments lead.<br>
-- Norbert Wiener
</div>
</div>
</blockquote>
<br>
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