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? |