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MathGroup Archive 2005

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Re: function of a function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg62628] Re: function of a function
  • From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
  • Date: Tue, 29 Nov 2005 06:44:10 -0500 (EST)
  • Organization: Uni Leipzig
  • References: <dmha20$932$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

it can't work because f[0]==1 give in your 
differential equation
f'[0]==f[1] and NDSolve[] can't find the value for 
f[1] until it
has integrated the equation.
The neted dependence is equvalent to a infinite 
system of
ordinary differential equations and it seems to be 
hard to do
this by a finte computer.

Regards
  Jens

"Narasimham" <mathma18 at hotmail.com> schrieb im 
Newsbeitrag news:dmha20$932$1 at smc.vnet.net...
| Tried to solve numerically:
|
| 
http://groups.google.com/group/sci.math/browse_frm/thread/248f76d024c1ac57/0bba983777a07bc9#0bba983777a07bc9
|
| thus:
|
| EQ= { f'[x] == f[f[x]], f[0]== 1} ; 
NDSolve[EQ,f,{x,0,2}];
|
| But gives an error.  NDSolve::ndnum: 
Differential equation does not
| evaluate to a number at x = 0.
|
| Also does not work even with other f[0] values. 
Any way to do that?
| 



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