On Thu, Oct 21, 2010 at 4:46 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;">
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><br></div><div>You SNES is not converging. You solve 163 systems, but do 4300 function evaluations.</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;">
Thanks<br>
<br>
Xuan<br>
<br>
<br>
<br></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>