<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman,new york,times,serif;font-size:12pt"><div>Hi Frank,<br>
<br>
I used the same options, same starting points and same obj function, and
all other thing are the same too. (using linear system solver ma57).
(and used the hessian approximation). But sometime ipopt can find the
optimal point, but sometime can't.<br>
<br>
I found that ipopt provide different number of iteraitons for the same
problem.<br>
So I guess there are "something" random that existed in the ipopt
method.<br>
Does it relate to my question?<br>
Thx<br>
<br>
Lewis</div><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><font size="2" face="Tahoma"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> Frank E. Curtis <frank.e.curtis@gmail.com><br><b><span style="font-weight: bold;">To:</span></b> Lewis I <lewis369lewis@yahoo.com><br><b><span style="font-weight: bold;">Cc:</span></b> ipopt@list.coin-or.org<br><b><span style="font-weight: bold;">Sent:</span></b> Fri, March 26, 2010 5:08:23 AM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [Ipopt] Why sometimes can solve, but sometimes can't solve with the same problem?<br></font><br>
<div>Hi Lewis,</div><div><br></div><div>I suspect you'll need to answer a few questions before anyone can help you figure out what's really going on here.</div><div><br></div><div>1.) Naturally, if, say, your function evaluations involve random quantities, than the results can differ from run to run. (I'm guessing that's not your case, though.)</div>
<div>2.) If you are changing any of the options, then the results can certainly vary, even for the same problem.</div><div>3.) If you are running different versions of Ipopt, or if you're running even the same version on different platforms, things can change.</div>
<div><br></div><div>If it's not any of these basic things, we'd probably need to know more about your problem, the options you're using (including the linear system solver), etc.</div><br><div class="gmail_quote">
On Thu, Mar 25, 2010 at 5:00 PM, Lewis I <span dir="ltr"><<a rel="nofollow" ymailto="mailto:lewis369lewis@yahoo.com" target="_blank" href="mailto:lewis369lewis@yahoo.com">lewis369lewis@yahoo.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Dear all,<br>
<br>
Why ipopt sometimes can solve, but sometimes can't solve with the same problem?<br>
And the number of iteration are different too.why?<br>
<br>
Regards,<br>
Lewis<br>
<br>
<br>
<br>
<br>
<br>
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