On Thu, Oct 21, 2010 at 5:02 PM, Xuan Yu <span dir="ltr"><<a href="mailto:xxy113@psu.edu">xxy113@psu.edu</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div style="word-wrap:break-word"><br><div><div>On Oct 21, 2010, at 5:56 PM, Matthew Knepley wrote:</div><br><blockquote type="cite">On Thu, Oct 21, 2010 at 4:46 PM, Xuan Yu <span dir="ltr"><<a href="mailto:xxy113@psu.edu" target="_blank">xxy113@psu.edu</a>></span> wrote:<br>
<div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi<br>
<br>
<br>
I am using Petsc solve ODE nonlinear problem.<br>
<br>
I was told to use direct method: umfpackage because of the jacobian matrix is 1860 by 1860.<br>
<br>
But the time consumption is still too big:<br>
<br>
TSSetType(ts,TSBEULER)<br>
<br>
time ./pihm -log_summary -ksp_type preonly -pc_type lu -pc_factor_mat_solver_package umfpack<br>
<br>
I got the result:<br>
<br><br>
When I use TSSetType(ts,TSSUNDIALS), it is fast:<br>
<br>
<br><br>
How can I find the reason why BEULER is so slow?<br></blockquote><div class="im"><div><br></div><div>You SNES is not converging. You solve 163 systems, but do 4300 function evaluations.</div></div></div></blockquote><div>
<br></div><div>Could you please tell me more solution options or possible mistakes in my code?</div></div></div></blockquote><div><br></div><div>Jed, is right. You are using coloring with a lot of colors. Sundials is doing much better</div>
<div>than backwards-Euler, why not just use it?</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div style="word-wrap:break-word">
<div><blockquote type="cite"><div class="gmail_quote"><div> Matt</div><div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Thanks<br>
<br>
Xuan<br>
<br>
<br>
<br></blockquote></div><div class="im"><br><br clear="all"><br>-- <br>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<br>
</div></blockquote></div><br></div></blockquote></div><br><br clear="all"><br>-- <br>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<br>