Re: using InterpolationFunction in NDSolve
- To: mathgroup at smc.vnet.net
- Subject: [mg42573] Re: [mg42552] using InterpolationFunction in NDSolve
- From: Selwyn Hollis <selwynh at earthlink.net>
- Date: Wed, 16 Jul 2003 09:13:35 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Rich, You just need to pull the solution out of the list that it's in. Try this: sol=NDSolve[{f'[x]==E^-x,f[0]==0},f[x],{x,0,1}]; fi[x_] = First[ f[x]/.sol ]; NDSolve[{f'[x]==fi[x],f[0]==0},f[x],{x,0,1}] ----- Selwyn Hollis http://www.math.armstrong.edu/faculty/hollis On Tuesday, July 15, 2003, at 02:54 AM, Hammond, Richard (Civ, ARL/ARO) wrote: > Hi, > > How can you use an InterpolationFunction object > in NDSolve? For example suppose you define > > sol=NDSolve[{f'[x]==E^-x,f[0]==0},f[x],{x,0,1}] > fi[x_]:=Evaluate[f[x]/.sol] > > Ok, now we have fi[x], but if I try to use it in > NDSolve, or even NSolve, it does not work (although > I can do an NIntegrate with it, and of course plot it). > > The same, or related, problems occurs if fi[x] is defined > from NIntegrate. > > Thanks > > > Rich Hammond > > >