<span class="Apple-style-span" style="border-collapse: collapse; "><div>Hi Rebecca,</div>Thanks for reminding me the half-spacing strategy, the 3*7 restriction matrix in 1-D.<div><br></div><div><div><font color="#888888">Yan</font></div>
</div></span><br><div class="gmail_quote">On Tue, Dec 15, 2009 at 10:37 PM, (Rebecca) Xuefei YUAN <span dir="ltr"><<a href="mailto:xy2102@columbia.edu">xy2102@columbia.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Now PETSc treats the multigrid based on the half spacing strategy, thus they always do odd number of grids.<div><div></div><div class="h5"><br>
<br>
R<br>
<br>
Quoting Ryan Yan <<a href="mailto:vyan2000@gmail.com" target="_blank">vyan2000@gmail.com</a>>:<br>
<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div></div><div class="h5">
Sorry, I forgot to cc to the group.<br>
<br>
BTW, if this is designed to have only odd number of points on the finer<br>
level grid, can anyone provide a hint on the reasoning behind this?<br>
<br>
Thanks a lot,<br>
<br>
Yan<br>
<br>
On Tue, Dec 15, 2009 at 10:09 PM, Ryan Yan <<a href="mailto:vyan2000@gmail.com" target="_blank">vyan2000@gmail.com</a>> wrote:<br>
<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div></div><div class="h5">
Hi Rebecca,<br>
Thanks for the info. I noticed that rule; yet, it seems very difficult to<br>
bring up a finest grid with *even* number of pts.<br>
<br>
Yan<br>
<br>
<br>
On Tue, Dec 15, 2009 at 9:55 PM, (Rebecca) Xuefei YUAN <<br>
<a href="mailto:xy2102@columbia.edu" target="_blank">xy2102@columbia.edu</a>> wrote:<br>
<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div></div><div class="h5">
The relation between the coarser grid and finer grid is always half<br>
spacing in either x-, y-, or z-direction.<br>
<br>
Thus, for your finest grid being 257x257x257, you need a coarser grid of<br>
129x129x129 on the coarse grid if your level is 2.<br>
<br>
Hope this is helpful.<br>
<br>
R<br>
<br>
<br>
<br>
Quoting Ryan Yan <<a href="mailto:vyan2000@gmail.com" target="_blank">vyan2000@gmail.com</a>>:<br>
<br>
Hi All,<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I was ignoring the importance of fixing the mesh size.<br>
For instance, if I want to compare the effect of mesh sequencing on the<br>
solver, I will use one level with 256 pt on each direction in 2d, in the<br>
first run.<br>
<br>
My question is, in the second run, how to set up the number of points on<br>
the coarsest grid and pre-fix the level of the grid so that DMMG<br>
can bring me the exact resolution of 256 pt on each direction on the<br>
finest<br>
grid. Only this way, the two different solver are solving the problem of<br>
the<br>
same<br>
size.<br>
<br>
Thanks a lot,<br>
<br>
Yan<br>
<br>
<br>
</blockquote>
<br>
<br>
--<br>
(Rebecca) Xuefei YUAN<br>
Department of Applied Physics and Applied Mathematics<br>
Columbia University<br>
Tel:917-399-8032<br>
</div></div><a href="http://www.columbia.edu/~xy2102" target="_blank">www.columbia.edu/~xy2102</a> <<a href="http://www.columbia.edu/%7Exy2102" target="_blank">http://www.columbia.edu/%7Exy2102</a>><br>
<br>
<br>
</blockquote>
<br>
</blockquote>
<br>
</blockquote><div><div></div><div class="h5">
<br>
<br>
<br>
-- <br>
(Rebecca) Xuefei YUAN<br>
Department of Applied Physics and Applied Mathematics<br>
Columbia University<br>
Tel:917-399-8032<br>
<a href="http://www.columbia.edu/~xy2102" target="_blank">www.columbia.edu/~xy2102</a><br>
<br>
</div></div></blockquote></div><br>