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On Fri, Feb 23, 2024 at 9: 54 AM 袁煕 <yuanxi@ advancesoft. jp> wrote: Hello, I cannot fetch right values of a local vector after a second time calling DMSetLocalSection. My program runs like ==================== call PetscSectionSetup(section1,ierr)
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<div dir="ltr"><div dir="ltr">On Fri, Feb 23, 2024 at 9:54 AM 袁煕 <<a href="mailto:yuanxi@advancesoft.jp">yuanxi@advancesoft.jp</a>> wrote:<br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="msg1430850183110990287">
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Hello, I cannot fetch right values of a local vector after a second time calling DMSetLocalSection. My program runs like ==================== call PetscSectionSetup(section1,ierr) call DMSetLocalSection(dm_mesh,section1,ierr)call PetscSectionDestroy(section1,ierr)call
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<div dir="ltr"><span style="color:rgb(80,0,80)"><div><span style="color:rgb(0,0,0)">Hello,</span><font color="#000000"><br></font></div><div><span style="color:rgb(0,0,0)"><br></span></div><div><span style="color:rgb(0,0,0)">I cannot fetch </span>right values of a local vector after a second time calling DMSetLocalSection. My program runs like</div><div><span style="color:rgb(0,0,0)"><br></span></div><div><font color="#000000">====================</font></div><div>call PetscSectionSetup(section1,ierr)<font color="#000000"><br></font></div><div>call DMSetLocalSection(dm_mesh,section1,ierr)<br></div><div>call PetscSectionDestroy(section1,ierr)</div><div><br></div><div>call DMCreateGlobalVector(dm_mesh,vec_a,ierr)<br></div><div><br></div><div>call VecDestroy(vec_a,ierr)<br></div></span><div>call DMClearLocalVectors(dm_mesh, ierr);</div></div></div></blockquote><div><br></div><div>You also need to wipe out the SF,</div><div><br></div><div> call DMSetSectionSF(dm, PETSC_NULL_PETSCSF, ierr)</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="msg1430850183110990287"><div dir="ltr"><span style="color:rgb(80,0,80)"><div>call PetscSectionSetup(section2,ierr)<br></div><div>call DMSetLocalSection(dm_mesh,section2,ierr)<br></div><div><br></div><div>call DMCreateGlobalVector(dm_mesh,vec_a,ierr)<br></div></span><div>call DMGetLocalVector(dm_mesh,lvec,ierr);<br>call DMGlobalToLocal(dm_mesh,vec_a,INSERT_VALUES,lvec,ierr)<br>call VecGetArrayReadF90(lvec,tempv,ierr)<br>call VecGetArrayReadF90(vec_a,tempv1,ierr)<br>========================</div><div><br></div><div>In this program, I got two Fortran style arrays, <i><u><b>tempv</b></u></i> and <u><b><i>tempv1</i></b></u>, from a Vec <b><i><u>vec_a</u></i></b>. When only 1 cpu is used, those two arrays should be completely the same. Am I right? But I found there are differences as follows:</div><div><br></div><div>* In array <i><u><b>tempv</b></u></i>, dofs newly introduced by section2 are zero valued. Looks like those values are ignored by DMGlobalToLocal. But in array <u><b><i>tempv1</i></b></u>, all dofs values are set correctly. </div><div><br></div><div>Did I do something wrong in the above code?</div></div></div></blockquote><div> <br></div><div>We do not usually reset the section on a DM. Instead, when we want to use a different function space,</div><div>we clone the DM, using DMClone(), and make a new function space on the new DM.</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:1px solid rgb(204,204,204);padding-left:1ex"><div class="msg1430850183110990287"><div dir="ltr"><div><div>Much thanks for your help.</div><div><br></div><div>X. Yuan, Ph.D. in Solid Mechanics</div></div></div>
</div></blockquote></div><br clear="all"><div><br></div><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>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><br></div><div><a href="https://urldefense.us/v3/__http://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!bAsyX_068Z0c_UIQmCwlZXop22TY8QcA8rRgki-yA9aSOze_tjnsWkrWUfzE8KpRNzzHsqLXQwFSADY8jt9N$" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><br></div></div></div></div></div></div></div></div>