On Thu, May 17, 2012 at 2:43 PM, Zhenglun (Alan) Wei <span dir="ltr"><<a href="mailto:zhenglun.wei@gmail.com" target="_blank">zhenglun.wei@gmail.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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On 5/17/2012 1:11 PM, Matthew Knepley wrote:
<blockquote type="cite">On Thu, May 17, 2012 at 1:47 PM, Zhenglun (Alan) Wei <span dir="ltr"><<a href="mailto:zhenglun.wei@gmail.com" target="_blank">zhenglun.wei@gmail.com</a>></span>
wrote:<br>
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Dear All,<br>
I hope you're having a nice day.<br>
I was trying to solve the Poisson equation with
/src/ksp/ksp/exmaples/tutorial/ex45.c; however, it always give
me the same result. I recalled the PetscLogStages and resolved
this problem. However, the process of reconstructing DM costs
a lot of computational time. I wonder do I have to use
PetscLogStages to solve this problem, since, I thought, this
function is only needed for using DMMG. Or as long as DM twice
in one program, then I need to call PetscLogStages.<br>
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<div>I cannot understand what you mean. PetscLog functions only
affect logging.</div>
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<div> Matt</div>
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<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
thanks,<br>
Alan<br>
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-- <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<br>
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Dear Dr. Knepley, <br>
I'm sorry for confusing you. Here I attached a old version of
/src/ksp/ksp/examples/tutorials/ex50.c. By adopting its approach of
PetscLogStage, I can solve Poisson equation twice with two different
RHS in one program. However, as you may noticed, this method, in
ex50.c, is used for DMMG. What I understand is that the DMMG has a
severe limitation so that the PetscLogStage is needed in order to
solve the equation twice with two different RHS. I wonder if I have
to use this approach for KSP? This method requires a lot of time to
KSPCreate and DMMGCreate3d/2d in order to construct the DM. That's
why I want to find an alternative way.<br></div></blockquote><div><br></div><div>No, PetscLogStage has nothing to do with solving with different RHS. It is only there so you can separately time the solves.</div><div>
<br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#FFFFFF" text="#000000">
thanks,<br>
Alan <br>
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</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<br>