Re: right StoppingTest

*To*: mathgroup at smc.vnet.net*Subject*: [mg31766] Re: right StoppingTest*From*: atelesforos at hotmail.com (Orestis Vantzos)*Date*: Sat, 1 Dec 2001 02:45:03 -0500 (EST)*References*: <9tvgln$fql$1@smc.vnet.net> <9u20bm$ipa$1@smc.vnet.net> <9u4h3q$lpl$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

It's a better-safe-than-dead thing, in this case. Generaly, you don't want the test to be evaluated BEFORE the solution gets going (as would be the case with an 'ordinary' ->), but only within the NDSolve code, so we use :> (RuleDelayed). For instance: NDSolve[.....,StoppingTest->(Print[t];False)] would return something like this: t Out[13]:= -InterpolatingFunction- which is not what you want! If you use the same command with a :> instead of ->, you will get all the t's, that are used as intermediate steps, printed and the interpolating function returned as desired. Orestis