Re: Getting the value of the independent var from the dep.var using NDSolve
- To: mathgroup at smc.vnet.net
- Subject: [mg63708] Re: [mg63667] Getting the value of the independent var from the dep.var using NDSolve
- From: Pratik Desai <pdesai1 at umbc.edu>
- Date: Tue, 10 Jan 2006 04:50:34 -0500 (EST)
- References: <200601090949.EAA29672@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
pradeep suresh wrote: >Hi all, >i have a specific problem of finding the point at which the dependent >variable takes on a particular value in teh solution of a differential >equation. >e.g. for simplicity >we have the equation y'[t]==t, and the initial cond. y[0]==0.y is the >dep. variable and t is the independent variable. >i want to find out the 't' at which y[t]==p(p is known, say 8) >and since i am already using NDSolve to solve this and other equations >i'd like to achieve this working around NDSolve, >could anyone suggets a solution to this problem?? >thanks a ton! >Pradeep > > > I think this is possible in Ver 5.2, here is a link with a nice example using widget by Robert Knapp http://library.wolfram.com/infocenter/Conferences/5817/ For pre 5.2 I think if you look at EvaluationMonitor it will give you some work around. Here is one that I modified a bit ww=Reap[Sow[NDSolve[{x''[t]+x[t]==0,x[0]==1,x'[0]==0},x,{t,0,2Ï?},Methodï?¢"ExplicitRungeKutta",StepMonitorï??Sow[t,"Steps"], EvaluationMonitorï??Sow[{t,x[t],x'[t]}]]]]; TableForm[Most[ww[[2,1]]],TableHeadings->{Automatic,{"t","x[t]","x'[t]"}} I have never used Reap and Sow so some of the functionality is still unclear to me?? Hope this helps Pratik
- References:
- Getting the value of the independent var from the dep.var using NDSolve
- From: pradeep suresh <pradeep@purdue.edu>
- Getting the value of the independent var from the dep.var using NDSolve