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?
>
>