Re: How do I get a DSolve'd function

*To*: mathgroup at smc.vnet.net*Subject*: [mg54407] Re: [mg54384] How do I get a DSolve'd function*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Sun, 20 Feb 2005 00:08:09 -0500 (EST)*Reply-to*: hanlonr at cox.net*Sender*: owner-wri-mathgroup at wolfram.com

Clear[f]; f[x_] = f[x] /. DSolve[{f'[x]==-3f[x],f[0]==10},f,x][[1]]; f[x] 10/E^(3*x) Bob Hanlon > > From: skirmantas.janusonis at yale.edu (Skirmantas) To: mathgroup at smc.vnet.net > Date: 2005/02/19 Sat AM 02:33:01 EST > To: mathgroup at smc.vnet.net > Subject: [mg54407] [mg54384] How do I get a DSolve'd function > > I hope this is the last question for now. > > I can solve a differential equation and plot it by doing something > like this: > > sol=DSolve[{f'[x]==-3f[x],f[0]==10},f,x] > Plot[f/.sol,{x,0,10}] > > But how do I get the function f[x] itself? I want to be able to input > f[x] and get its definition. Or do Plot[f[x],{x,0,10}]. Or define > y[x_]:=f[x]^2. > > f[x]/.sol or f[x_]:=f[x]/.sol or f[x_]:=sol[[n,n,n]] do not work. > > What if the solution is a function with many variables, say u[x,y,z]? > What's the correct way to "get" it? > >