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MathGroup Archive 2005

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Re: How do I get a DSolve'd function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg54440] Re: [mg54384] How do I get a DSolve'd function
  • From: Chris Chiasson <chris.chiasson at gmail.com>
  • Date: Sun, 20 Feb 2005 00:10:22 -0500 (EST)
  • References: <200502190733.CAA06184@smc.vnet.net>
  • Reply-to: Chris Chiasson <chris.chiasson at gmail.com>
  • Sender: owner-wri-mathgroup at wolfram.com

This will work for your purposes:

Block[{f = dummyfunction},
  sol = DSolve[{f'[x] == -3f[x], f[0] == 10}, f, x]]
f = dummyfunction /. sol[[1]]
Plot[f[x], {x, 0, 10}]

Regards,


On Sat, 19 Feb 2005 02:33:01 -0500 (EST), Skirmantas
<skirmantas.janusonis at yale.edu> 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[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?
> 
> 


-- 
Chris Chiasson
Kettering University
Mechanical Engineering
Graduate Student
1 810 265 3161


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