<div class="gmail_quote">On Wed, Jun 15, 2011 at 18:54, Alexander Grayver <span dir="ltr"><<a href="mailto:agrayver@gfz-potsdam.de">agrayver@gfz-potsdam.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div id=":1xg">I've got simple question.<br>
What is the most efficient way to compute B = A'*A using petsc?<br>
Matrix A is sparse MPIAIJ.</div></blockquote></div><br><div>What are you going to do with B = A'*A?</div><div><br></div><div>The most efficient thing is MatCreateTranspose() which does no computation.</div><div><br></div>
<div><a href="http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/Mat/MatCreateTranspose.html">http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/Mat/MatCreateTranspose.html</a></div>
<div><br></div><div><br></div><div>If you need B assembled, then create a diagonal matrix and use MatPtAP()</div><div><br></div><div><a href="http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/Mat/MatPtAP.html">http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/Mat/MatPtAP.html</a></div>