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Re: How do I get a DSolve'd function


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?  
> 
> 


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