Re: Garbage collection problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg51965] Re: Garbage collection problem*From*: D Herring <dherring at at.uiuc.dot.edu>*Date*: Fri, 5 Nov 2004 02:20:04 -0500 (EST)*References*: <cm7d0u$lho$1@smc.vnet.net> <200411030626.BAA08435@smc.vnet.net> <cmckmc$i47$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

> That's an odd bug; but I kind of doubt StoppingTest is working well for you ANYWAY. I don't know what you mean by that... StoppingTest is a bit awkward to work with, but I've found ways to manage, and its performing beautifully - if you can ignore the memory leak. Essentially, I have a dynamical system that regularly impacts with a rigid surface. By setting the StoppingTest to halt NDSolve shortly *after* the impact has occurred, I can save a lot of simulation time, and it makes it easier to find the exact impact point. I'm essentially doing the following: (* Expect impact around 0.5; but can happen after 2 *) soln=NDSolve[eqn, vars, {t, 0, 3}, StoppingTest->test]; (* Detect where NDSolve stopped *) tau=(vars[[1]]/.soln)[[0, 1, 1, 2]] (* Find the exact surface intersection *) tImpact=FindRoot[surface/.soln, {t, tau}]; Because of the highly nonlinear behavior of my system, FindRoot won't converge unless I give it a reasonably good estimate of the intersection time. StoppingTest gives me that and stops NDSolve as soon as possible. If you have any better ideas, I'm all ears. Thanks, Daniel

**Follow-Ups**:**Re: Re: Garbage collection problem***From:*DrBob <drbob@bigfoot.com>

**References**:**Re: Garbage collection problem***From:*sean_incali@yahoo.com (sean kim)