Dear Dr. Smith,<div> I figure out this problem. Actually, I made my own RHS, but I did not multiply them by the volume (dx*dy). </div><div> However, I met another problem. All values calculated from this example are exactly opposite to values from my own code. I wonder if the RHS I input by ComputeRHS are the really RHS or -1.*RHS?</div>
<div><br></div><div>thanks in advance,</div><div>Alan<br><br><div class="gmail_quote">On Mon, Sep 19, 2011 at 8:43 PM, Barry Smith <span dir="ltr"><<a href="mailto:bsmith@mcs.anl.gov">bsmith@mcs.anl.gov</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div class="im"><br>
On Sep 19, 2011, at 6:25 PM, Alan Wei wrote:<br>
<br>
> Dear folks,<br>
> I hope you guys are having a nice day.<br>
> I'm reading the /src/ksp/ksp/examples/tutorials/ex29.c.html and wonder how to set up the convergence criteria?<br>
<br>
</div> -ksp_rtol 1.e-10 for example<br>
<br>
Run with -ksp_monitor_true_residual -ksp_converged_reason<br>
<div class="im"><br>
<br>
> Currently I use it as a poisson solver to solve a Poisson Equation with three direction Neumann BC's and one direction Diriechlet BC's. It seems very bad on it.<br>
<br>
</div> Hmm, multigrid should likely converge well. Are you sure you've set the BC's correctly?<br>
<br>
Barry<br>
<br>
><br>
> thanks in advance,<br>
> Alan<br>
<br>
</blockquote></div><br></div>