<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Feb 4, 2008, at 12:20 PM, Yujie wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">what is the difference between sequantial and parallel AIJ matrix? Assuming there is a matrix A, if I partitaion this matrix into A1, A2, Ai... An.<br>A is a parallel AIJ matrix at the whole view, Ai is a sequential AIJ matrix? </blockquote><div><br class="webkit-block-placeholder"></div><div> It is not that simple. Ai is split into two parts 1) the "block diagonal" part and 2) the "off diagonal part" ; this is explained</div><div>in the manual page for MatCreateMPIAIJ(). If you want to do operations on the pieces you will need to understand the</div><div>code in src/mat/impls/aij/mpi. </div><div><br class="webkit-block-placeholder"></div><div> What do you want to do with Ai? </div><br><blockquote type="cite">I want to operate Ai at each node. <br> In addition, whether is it possible to get general inverse using MatMatSolve() if the matrix is not square? </blockquote><div><br class="webkit-block-placeholder"></div> No, that requires much more complicated linear algebra technology then is in PETSc.</div><div><br class="webkit-block-placeholder"></div><div> Barry</div><div><br><blockquote type="cite">Thanks a lot.<br> <br>Regards,<br>Yujie<br> <br><br><div><span class="gmail_quote">On 2/4/08, <b class="gmail_sendername">Barry Smith</b> <<a href="mailto:bsmith@mcs.anl.gov">bsmith@mcs.anl.gov</a>> wrote:</span><blockquote class="gmail_quote" style="margin-top: 0; margin-right: 0; margin-bottom: 0; margin-left: 0; margin-left: 0.80ex; border-left-color: #cccccc; border-left-width: 1px; border-left-style: solid; padding-left: 1ex"> <br> For sequential AIJ matrices you can fill the B matrix with the<br>identity and then use<br>MatMatSolve().<br><br> Note since the inverse of a sparse matrix is dense the B matrix is<br>a SeqDense matrix.<br><br> Barry<br><br>On Feb 4, 2008, at 12:37 AM, Yujie wrote:<br><br>> Hi,<br>> Now, I want to inverse a sparse matrix. I have browsed the manual,<br>> however, I can't find some information. could you give me some advice?<br> ><br>> thanks a lot.<br>><br>> Regards,<br>> Yujie<br>><br><br></blockquote></div><br></blockquote></div><br></body></html>