<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><br class="webkit-block-placeholder"></div> They should be pretty much the same. In both cases the huge bulk of the time<div>is spent in the triangular solves.</div><div><br class="webkit-block-placeholder"></div><div> Barry</div><div><br><div><div>On Feb 4, 2008, at 8:04 AM, Dave May wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">Hi,<br> Does anyone know how much faster (approximately) using MatMatSolve is compared<br>to using PCComputeExplicitOperator(), when the PC in the latter function is defined to be LU?<br><br>Cheers,<br> Dave.<br><br> <br><div class="gmail_quote">On Feb 5, 2008 12:10 AM, Barry Smith <<a href="mailto:bsmith@mcs.anl.gov">bsmith@mcs.anl.gov</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; 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><font color="#888888"><br> Barry<br></font><div><div></div><div class="Wj3C7c"><br><br></div></div></blockquote></div></blockquote></div><br></div></body></html>