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<div class="moz-cite-prefix">Dear Matt,<br>
Yes. if I only double the dx, then, the mesh has been changed
are on z=0 plane and y = 0 plane. Similarly, if the dz is doubled,
the mesh has been changed are only on x = 0 plane and y = 0 plane
(see the picture attached). <br>
Moreover, if I double all direction (i.e. dx = dy = dz =
0.2), the mesh is shown in the picture 'doubleAll' in the
attachment. It seems that the mesh generated by the
'DMDASetUniformCoordinate' is always there. <br>
<br>
best,<br>
Alan<br>
<br>
On 2/28/2013 7:25 PM, Matthew Knepley wrote:<br>
</div>
<blockquote
cite="mid:CAMYG4GnhSKJx6X3MH=F3C3WUBLRbqq04Lkuq-=hvfUWTEOmymg@mail.gmail.com"
type="cite">
<div dir="ltr">On Thu, Feb 28, 2013 at 8:05 PM, Zhenglun (Alan)
Wei <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:zhenglun.wei@gmail.com" target="_blank">zhenglun.wei@gmail.com</a>></span>
wrote:<br>
<div class="gmail_extra">
<div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div>Dear Matt,<br>
Thanks for your reply on the 1st question and I'm
sorry for the confusion on the 2nd one. <br>
In order to create a non-uniform Cartesian grid, I
expected that the way I was programming can let me
freely control the grid size. In the code attached in
the previous E-mail, the 'DMDASetUniformCoordinate'
generates a uniform coordinate with 100*48*48 grid
number and 0.1*0.1*0.1 grid size. I was trying to
manually double the grid size in the y-direction for
the whole mesh with operations of DMDA in the
'SetNonUniformGrid()', which follows the method that
/src/ksp/ksp/examples/tutorials/ex49.c used. However,
as you can see in the figure attached in the previous
E-mail, only the mesh on z = 0 plane and x = 0 plane
has been changed to dy = 0.2; while I expected all
mesh should have dy = 0.2 after I call
'SetNonUniformGrid()'. <br>
Any idea about this?<br>
</div>
</div>
</blockquote>
<div><br>
</div>
<div style="">Were you looking over all 3 directions?</div>
<div style=""><br>
</div>
<div style=""> Matt</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div> thanks,<br>
Alan<br>
<br>
On 2/28/2013 6:31 PM, Matthew Knepley wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">On Thu, Feb 28, 2013 at 7:19 PM,
Zhenglun (Alan) Wei <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:zhenglun.wei@gmail.com"
target="_blank">zhenglun.wei@gmail.com</a>></span>
wrote:<br>
<div class="gmail_extra">
<div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0
0 0 .8ex;border-left:1px #ccc
solid;padding-left:1ex">Dear folks,<br>
Here are several questions following up my
previous ones:<br>
1, I modified my code based on ex49.c.
However, I found that if I don't call
'DMDASetUniformCoordinates' before calling
'DMDAVecGetArray', then an error comes up:<br>
[0]PETSC ERROR: Null argument, when expecting
valid pointer!<br>
[0]PETSC ERROR: Null Object: Parameter # 2!<br>
The code do works if I add a call for
'DMDASetUniformCoordinates' in it. However, I
feel it is a waste of calling
'DMDASetUniformCoordinates' since what follows
this calling is to change the coordinate to a
non-uniform gird. Does it have any way to
bypass this call or you think it is fine to
keep it here.<br>
</blockquote>
<div><br>
</div>
<div>If you do not call it, then you have to
create the coordinate vector yourself. I would
just call it.</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0
0 0 .8ex;border-left:1px #ccc
solid;padding-left:1ex"> 2, Also, if I do by
this way, the outputted mesh looks weird, as
shown in the figure.<br>
I was trying to double the dy value
manually in the SetNonUniformGrid(). However,
the only mesh changed is just on the z=0 and
x=0 plane. Here I attached my code. Do I need
to do anything else except
DMDAVecRestoreArray() after I modified the
coordinate information?<br>
</blockquote>
<div><br>
</div>
<div>I do not understand what you want here.</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"> thanks,<br>
Alan<br>
<br>
<br>
On 2/26/2013 8:46 PM, Barry Smith wrote:<br>
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex"> On Feb 26,
2013, at 4:49 PM, "Zhenglun (Alan) Wei"<<a
moz-do-not-send="true"
href="mailto:zhenglun.wei@gmail.com"
target="_blank">zhenglun.wei@gmail.com</a>>
wrote:<br>
<br>
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex"> Dear folks,<br>
I have one question for the ex49.<br>
It do show a way to 'get' the
'coord' by the 'DMDAVecGetArray'. Should I
just modified the coordinate on the
'coord' in order to obtain a non-uniform
grid? and then, use DMDAVecRestoreArray to
link the modified 'coord' back to 'cda' so
that the 'coord' will be updated to the
mesh I want?<br>
</blockquote>
Yes, you can do this.<br>
<br>
<br>
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex"> thanks,<br>
Alan<br>
<br>
On 2/22/2013 3:20 PM, Matthew Knepley
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex"> On Fri,
Feb 22, 2013 at 3:57 PM, Zhenglun (Alan)
Wei<<a moz-do-not-send="true"
href="mailto:zhenglun.wei@gmail.com"
target="_blank">zhenglun.wei@gmail.com</a>>
wrote:<br>
Dear all,<br>
I hope you're having a nice day.<br>
I wonder if anyone could point out a
example for me about the<br>
DMDASetCoordinates(). I found this<br>
(<a moz-do-not-send="true"
href="http://www.mcs.anl.gov/petsc/petsc-current/src/dm/impls/da/dacorn.c.html#DMDASetCoordinates"
target="_blank">http://www.mcs.anl.gov/petsc/petsc-current/src/dm/impls/da/dacorn.c.html#DMDASetCoordinates</a>)<br>
online; however it does not really
demonstrate how to create the<br>
'coordinate vector - c'.<br>
Also, I found that in the petsc
sub-folder:<br>
/petsc-dev/src/dm/impls/patch has a
patch.c, which I suppose that it<br>
does a local refinement for mesh. Does
this a mature model that we can<br>
use or just a testing code?<br>
<br>
Look at KSP ex49. In the routine
DMDACoordViewGnuplot2d() it reads out
the coordinates.<br>
You could just as easily set them in
this fashion.<br>
<br>
Matt<br>
thanks,<br>
Alan<br>
<br>
On 11/7/2012 6:55 PM, Barry Smith wrote:<br>
<blockquote class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px #ccc
solid;padding-left:1ex"> On Nov 7,
2012, at 6:50 PM, Alan<<a
moz-do-not-send="true"
href="mailto:zhenglun.wei@gmail.com"
target="_blank">zhenglun.wei@gmail.com</a>>
wrote:<br>
<br>
<blockquote class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px #ccc
solid;padding-left:1ex"> Dear folks,<br>
I hope you're having a nice day.<br>
I'm testing the Poisson solver in
/src/ksp/ksp/examples/tutorials/ex45.<br>
It uses the 'DMDACreate3d' to
generate a Cartisian structured grid
and<br>
solve it with uniform grid size.
However, I attempt to modify it to<br>
obtain solution with a Cartsian
structured grid and non-uniform grid
(It<br>
is not unstructured local refined
mesh). Should I still use the<br>
'DMDACreate3d' and implement
different grid size in
'ComputeMatrix' and<br>
'ComputeRHS'? In other words, does
'DMDACreate3d' itself include any<br>
mesh size information?<br>
</blockquote>
You can use DMDASetCoordinates()
and DMDAGetCoordinates() (called
DMSetCoordinates() and
DMGetCoordinates() in petsc-dev) to
keep track of the coordinates but you
are responsible for generating the
correctly scaled entries in the matrix
etc.<br>
<br>
Barry<br>
<br>
<blockquote class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px #ccc
solid;padding-left:1ex"> thanks,<br>
Alan<br>
</blockquote>
</blockquote>
<br>
<span class="HOEnZb"><font
color="#888888"> <span><font
color="#888888"> <br>
-- <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>
</font></span></font></span></blockquote>
<span class="HOEnZb"><font color="#888888">
</font></span></blockquote>
<span class="HOEnZb"><font color="#888888">
</font></span></blockquote>
<span class="HOEnZb"><font color="#888888"> <br>
</font></span></blockquote>
<span class="HOEnZb"><font color="#888888"> </font></span></div>
<span class="HOEnZb"><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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