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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Thank for your response that was helpful. I have a couple of questions:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="margin-left:54.0pt;text-indent:-36.0pt;mso-list:l0 level1 lfo1">
<![if !supportLists]><span style="mso-fareast-language:EN-US"><span style="mso-list:Ignore">(i)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="mso-fareast-language:EN-US">How can I control the level of refinement? I tried to pass the flag “-ex56_dm_refine 0” but that didn’t stop the refinement from
</span>8 giving 32 cubes.<span style="mso-fareast-language:EN-US"><o:p></o:p></span></p>
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<![if !supportLists]><span style="mso-fareast-language:EN-US"><span style="mso-list:Ignore">(ii)<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]>What does -cell 2,2,1 correspond to? How can I determine the total number of dofs? So that I can perform a scaling study by changing the input of the flag -cells.<span style="mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Kind regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Karthik.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black">Matthew Knepley <knepley@gmail.com><br>
<b>Date: </b>Saturday, 11 December 2021 at 02:27<br>
<b>To: </b>"Chockalingam, Karthikeyan (STFC,DL,HC)" <karthikeyan.chockalingam@stfc.ac.uk><br>
<b>Cc: </b>"petsc-users@mcs.anl.gov" <petsc-users@mcs.anl.gov><br>
<b>Subject: </b>Re: [petsc-users] Unstructured mesh<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Fri, Dec 10, 2021 at 1:11 PM Karthikeyan Chockalingam - STFC UKRI <<a href="mailto:karthikeyan.chockalingam@stfc.ac.uk">karthikeyan.chockalingam@stfc.ac.uk</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Thank you that worked. I have attached the output of the run<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="gmail-m-483441426263388782p1"><span class="gmail-m-483441426263388782s1"><span style="font-size:10.0pt">./ex56 -cells 2,2,1 -max_conv_its 2 -lx 1. -alpha .01 -petscspace_degree 1 -ksp_type cg -ksp_monitor -ksp_rtol 1.e-8 -pc_type asm -snes_monitor
-use_mat_nearnullspace true</span></span><span class="gmail-m-483441426263388782apple-converted-space"><span style="font-size:10.0pt"> </span></span><span class="gmail-m-483441426263388782s1"><span style="font-size:10.0pt">-snes_rtol 1.e-10 -ex56_dm_view</span></span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Below is the mesh information I get before the solve.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Not sure how to interpret them – is ‘18’ say number of elements in certain direction?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">0-cells are vertices, 1-cells are edges, etc, so this has 4 cubes. That is why it has 18 vertices, 9 on top and 9 on the bottom. A<o:p></o:p></p>
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<p class="MsoNormal">bunch of stuff is labeled on this mesh, but you don't have to worry about it I think.<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">How does ‘18’ come about – given cells 2,2,1 as input?<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Sorry, bit lost what markers and other labels represent.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Mesh in 3 dimensions:<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> 0-cells: 18<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> 1-cells: 33<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> 2-cells: 20<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> 3-cells: 4<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Labels:<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> marker: 1 strata with value/size (1 (48))<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> Face Sets: 6 strata with value/size (6 (2), 5 (2), 3 (2), 4 (2), 1 (4), 2 (4))<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> depth: 4 strata with value/size (0 (18), 1 (33), 2 (20), 3 (4))<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> boundary: 1 strata with value/size (1 (66))<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> celltype: 4 strata with value/size (7 (4), 0 (18), 4 (20), 1 (33))<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I am more puzzled as the mesh information changes after the solve?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Mark refined it once regularly, so each hexahedron is split into 8, giving 32 cubes.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> Thanks,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> Matt<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="gmail-m-483441426263388782p1"><span class="gmail-m-483441426263388782s1"><span style="font-size:10.0pt">Mesh in 3 dimensions:</span></span><o:p></o:p></p>
<p class="gmail-m-483441426263388782p1"><span class="gmail-m-483441426263388782apple-converted-space"><span style="font-size:10.0pt">
</span></span><span class="gmail-m-483441426263388782s1"><span style="font-size:10.0pt">0-cells: 75</span></span><o:p></o:p></p>
<p class="gmail-m-483441426263388782p1"><span class="gmail-m-483441426263388782apple-converted-space"><span style="font-size:10.0pt">
</span></span><span class="gmail-m-483441426263388782s1"><span style="font-size:10.0pt">1-cells: 170</span></span><o:p></o:p></p>
<p class="gmail-m-483441426263388782p1"><span class="gmail-m-483441426263388782apple-converted-space"><span style="font-size:10.0pt">
</span></span><span class="gmail-m-483441426263388782s1"><span style="font-size:10.0pt">2-cells: 128</span></span><o:p></o:p></p>
<p class="gmail-m-483441426263388782p1"><span class="gmail-m-483441426263388782apple-converted-space"><span style="font-size:10.0pt">
</span></span><span class="gmail-m-483441426263388782s1"><span style="font-size:10.0pt">3-cells: 32</span></span><o:p></o:p></p>
<p class="gmail-m-483441426263388782p1"><span class="gmail-m-483441426263388782s1"><span style="font-size:10.0pt">Labels:</span></span><o:p></o:p></p>
<p class="gmail-m-483441426263388782p1"><span class="gmail-m-483441426263388782apple-converted-space"><span style="font-size:10.0pt">
</span></span><span class="gmail-m-483441426263388782s1"><span style="font-size:10.0pt">celltype: 4 strata with value/size (0 (75), 1 (170), 4 (128), 7 (32))</span></span><o:p></o:p></p>
<p class="gmail-m-483441426263388782p1"><span class="gmail-m-483441426263388782apple-converted-space"><span style="font-size:10.0pt">
</span></span><span class="gmail-m-483441426263388782s1"><span style="font-size:10.0pt">depth: 4 strata with value/size (0 (75), 1 (170), 2 (128), 3 (32))</span></span><o:p></o:p></p>
<p class="gmail-m-483441426263388782p1"><span class="gmail-m-483441426263388782apple-converted-space"><span style="font-size:10.0pt">
</span></span><span class="gmail-m-483441426263388782s1"><span style="font-size:10.0pt">marker: 1 strata with value/size (1 (240))</span></span><o:p></o:p></p>
<p class="gmail-m-483441426263388782p1"><span class="gmail-m-483441426263388782apple-converted-space"><span style="font-size:10.0pt">
</span></span><span class="gmail-m-483441426263388782s1"><span style="font-size:10.0pt">Face Sets: 6 strata with value/size (6 (18), 5 (18), 3 (18), 4 (18), 1 (36), 2 (36))</span></span><o:p></o:p></p>
<p class="gmail-m-483441426263388782p1"><span class="gmail-m-483441426263388782apple-converted-space"><span style="font-size:10.0pt">
</span></span><span class="gmail-m-483441426263388782s1"><span style="font-size:10.0pt">boundary: 1 strata with value/size (1 (258))</span></span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Best,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Karthik.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">Matthew Knepley <<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>><br>
<b>Date: </b>Friday, 10 December 2021 at 16:17<br>
<b>To: </b>"Chockalingam, Karthikeyan (STFC,DL,HC)" <<a href="mailto:karthikeyan.chockalingam@stfc.ac.uk" target="_blank">karthikeyan.chockalingam@stfc.ac.uk</a>><br>
<b>Cc: </b>"<a href="mailto:petsc-users@mcs.anl.gov" target="_blank">petsc-users@mcs.anl.gov</a>" <<a href="mailto:petsc-users@mcs.anl.gov" target="_blank">petsc-users@mcs.anl.gov</a>><br>
<b>Subject: </b>Re: [petsc-users] Unstructured mesh</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">On Fri, Dec 10, 2021 at 10:49 AM Karthikeyan Chockalingam - STFC UKRI <<a href="mailto:karthikeyan.chockalingam@stfc.ac.uk" target="_blank">karthikeyan.chockalingam@stfc.ac.uk</a>>
wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Thank you for your response.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I tried using the flag -dm_view to get mesh information.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I was hoping it might create a output file with mesh information but it didn’t create any.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">What should I expect with -dm_view?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">-dm_view prints the Plex information to the screen (by default), but it responds to the normal viewer options.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">However, it looks like Mark changes the prefix on the mesh, so I think you need<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> -ex56_dm_view<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> Thanks,<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> Matt<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Best,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Karthik.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">Matthew Knepley <<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>><br>
<b>Date: </b>Friday, 10 December 2021 at 13:04<br>
<b>To: </b>"Chockalingam, Karthikeyan (STFC,DL,HC)" <<a href="mailto:karthikeyan.chockalingam@stfc.ac.uk" target="_blank">karthikeyan.chockalingam@stfc.ac.uk</a>><br>
<b>Cc: </b>"<a href="mailto:petsc-users@mcs.anl.gov" target="_blank">petsc-users@mcs.anl.gov</a>" <<a href="mailto:petsc-users@mcs.anl.gov" target="_blank">petsc-users@mcs.anl.gov</a>><br>
<b>Subject: </b>Re: [petsc-users] Unstructured mesh</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">On Fri, Dec 10, 2021 at 7:42 AM Karthikeyan Chockalingam - STFC UKRI <<a href="mailto:karthikeyan.chockalingam@stfc.ac.uk" target="_blank">karthikeyan.chockalingam@stfc.ac.uk</a>>
wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hi Matt,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I intend to perform a scaling study – I have a few more questions from ex56<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;background:white">
<b><span style="font-size:10.0pt;font-family:"Courier New";color:black">3D, tri-quadratic hexahedra (Q1), displacement finite element formulation.</span></b><o:p></o:p></p>
<p class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028msolistparagraph" style="margin-left:54.0pt">
i)<span style="font-size:7.0pt;font-family:"Times New Roman",serif">
</span>What makes the problem non-linear? I believe SNES are used to solve non-linear problems.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">It is a linear problem. We use SNES because it is easier to use it for everything. <o:p></o:p></p>
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<p class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028msolistparagraph" style="margin-left:54.0pt">
ii)<span style="font-size:7.0pt;font-family:"Times New Roman",serif">
</span>2,2,1 does it present the number of elements used in each direction?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">You can use -dm_view to show the mesh information actually used in the run.<o:p></o:p></p>
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<p class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028msolistparagraph" style="margin-left:54.0pt">
iii)<span style="font-size:7.0pt;font-family:"Times New Roman",serif">
</span>What makes the problem unstructured? I believe the geometry is a cube or cuboid – is it because it uses DMPlex?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Yes. <o:p></o:p></p>
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<p class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028msolistparagraph" style="margin-left:54.0pt">
iv)<span style="font-size:7.0pt;font-family:"Times New Roman",serif">
</span>Do any external FEM package with an unstructured problem domain has to use DMPlex mat type?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">DMPlex is not a Mat type, but rather a DM type. I do not understand the question. For example, LibMesh uses PETSc solvers but has<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">its own mesh types. <o:p></o:p></p>
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<p class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028msolistparagraph" style="margin-left:54.0pt">
v)<span style="font-size:7.0pt;font-family:"Times New Roman",serif">
</span>What about -mat_type (not _dm_mat_type) ajicusparse – will it work with unstructured FEM discretised domains?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">dm_mat_type is just a way of setting the MatType that the DM creates. You can set it to whatever type you want. Since it uses MatSetValues()<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">there may be overhead in converting to that matrix type, but it should work.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I tried to run two problems of ex56 with two different domain size ( - attached you find the log_view outputs of both on<u>
</u><b>gpus</b>) using _pc_type asm:<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028p1">
<span class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028s1"><span style="font-size:10.0pt">./ex56 -cells 2,2,1 -max_conv_its 2 -lx 1. -alpha .01 -petscspace_degree 1 -ksp_type cg -ksp_monitor -ksp_rtol 1.e-8 -pc_type asm
-snes_monitor -use_mat_nearnullspace true</span></span><span class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028apple-converted-space"><span style="font-size:10.0pt">
</span></span><span class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028s1"><span style="font-size:10.0pt">-snes_rtol 1.e-10 > output_221.txt</span></span><o:p></o:p></p>
<p class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028p1">
<span class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028s1"><span style="font-size:10.0pt"> </span></span><o:p></o:p></p>
<p class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028p1">
<span style="font-size:10.0pt"> </span><o:p></o:p></p>
<p class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028p1">
<span class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028s1"><span style="font-size:10.0pt">./ex56 -cells 10,10,5 -max_conv_its 2 -lx 1. -alpha .01 -petscspace_degree 1 -ksp_type cg -ksp_monitor -ksp_rtol 1.e-8 -pc_type asm
-snes_monitor -use_mat_nearnullspace true</span></span><span class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028apple-converted-space"><span style="font-size:10.0pt">
</span></span><span class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028s1"><span style="font-size:10.0pt">-snes_rtol 1.e-10 > output_221.txt</span></span><o:p></o:p></p>
<p class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028p1">
<span class="gmail-m-483441426263388782gmail-m-6173748380162638319gmail-m-482615902856798028s1"><span style="font-size:10.0pt"> </span></span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Below is the SNES iteration for problem with 2,2,1 cells which converges after two non-linear iterations:<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">0 SNES Function norm 0.000000000000e+00
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> 0 SNES Function norm 7.529825940191e+01<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> 1 SNES Function norm 4.734810707002e-08<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> 2 SNES Function norm 1.382827243108e-14<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Your KSP tolerance is too high, so it takes another iterate. Use -ksp_rtol 1e-10.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Below is the SNES iteration for problem with 10,10,5 cells– why does it first decrease and then increase to
<b>0 SNES Function norm 1.085975028558e+01</b> and finally converge?<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> 0 SNES Function norm 2.892801019593e+01<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> 1 SNES Function norm 5.361683383932e-07
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> 2 SNES Function norm 1.726814199132e-14
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> 0 SNES Function norm 1.085975028558e+01<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> 1 SNES Function norm 2.294074693590e-07<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> 2 SNES Function norm 2.491900236077e-14<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">You are solving the problem twice, probably because ex56 is in its refinement loop.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> Thanks,<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> Matt<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Kind regards,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Karthik.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">Matthew Knepley <<a href="mailto:knepley@gmail.com" target="_blank">knepley@gmail.com</a>><br>
<b>Date: </b>Thursday, 2 December 2021 at 10:57<br>
<b>To: </b>"Chockalingam, Karthikeyan (STFC,DL,HC)" <<a href="mailto:karthikeyan.chockalingam@stfc.ac.uk" target="_blank">karthikeyan.chockalingam@stfc.ac.uk</a>><br>
<b>Cc: </b>"<a href="mailto:petsc-users@mcs.anl.gov" target="_blank">petsc-users@mcs.anl.gov</a>" <<a href="mailto:petsc-users@mcs.anl.gov" target="_blank">petsc-users@mcs.anl.gov</a>><br>
<b>Subject: </b>Re: [petsc-users] Unstructured mesh</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">On Thu, Dec 2, 2021 at 3:33 AM Karthikeyan Chockalingam - STFC UKRI <<a href="mailto:karthikeyan.chockalingam@stfc.ac.uk" target="_blank">karthikeyan.chockalingam@stfc.ac.uk</a>>
wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hello,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Are there example tutorials on unstructured mesh in ksp? Can some of them run on gpus?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">There are many unstructured grid examples, e.g. SNES ex13, ex17, ex56. The solver can run on the GPU, but the vector/matrix<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">FEM assembly does not. I am working on that now.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> Thanks,<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> Matt<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Kind regards,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Karthik.<o:p></o:p></p>
</div>
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<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">--
<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">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<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a href="http://www.cse.buffalo.edu/~knepley/" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">--
<o:p></o:p></p>
<div>
<div>
<div>
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<div>
<div>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">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<o:p></o:p></p>
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<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a href="http://www.cse.buffalo.edu/~knepley/" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><o:p></o:p></p>
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</blockquote>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><br clear="all">
<o:p></o:p></p>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">--
<o:p></o:p></p>
<div>
<div>
<div>
<div>
<div>
<div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">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<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a href="http://www.cse.buffalo.edu/~knepley/" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><o:p></o:p></p>
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</blockquote>
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<p class="MsoNormal"><br clear="all">
<o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<p class="MsoNormal">-- <o:p></o:p></p>
<div>
<div>
<div>
<div>
<div>
<div>
<div>
<p class="MsoNormal">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<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><a href="http://www.cse.buffalo.edu/~knepley/" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><o:p></o:p></p>
</div>
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