       Re: How do I get a DSolve'd function

• To: mathgroup at smc.vnet.net
• Subject: [mg54429] Re: How do I get a DSolve'd function
• From: Curt Fischer <tentrillion at gmail.NOSPAM.com>
• Date: Sun, 20 Feb 2005 00:09:48 -0500 (EST)
• References: <cv6t29\$6su\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Skirmantas wrote:
> 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==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?

In:=
sol=DSolve[{f'[x]\[Equal]-3f[x],f\[Equal]10},f,x];sol//InputForm

Out//InputForm=
{{f -> Function[{x}, 10/E^(3*x)]}}

In:=
g[y_]:=f[x]/.sol[]/.x -> y

In:=
g//InputForm

Out//InputForm=
10/E^3

--
Curt Fischer

```

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