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Re: Problem with combination NDSolve NIntegrate

  • To: mathgroup at smc.vnet.net
  • Subject: [mg72759] Re: Problem with combination NDSolve NIntegrate
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Thu, 18 Jan 2007 05:38:22 -0500 (EST)
  • Organization: Uni Leipzig
  • References: <eol09o$44r$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de

Hi,

Clear[trial]

trial[a_?NumericQ, where_] := (ti[t] /. NDSolve[{ti'[t] == ti[t], ti[0] ==
    a}, ti, {t, 0, 10}][[1]]) /. t -> where

NIntegrate[trial[a, 5], {a, 0, 10}]

and
Plot[trial[a, 5], {a, 0, 10}]

Regards
   Jens

Paul Schneider wrote:
> I am using version 5.2
> 
> 
> 
> NIntegrate tries to evaluate the integrand symbolically. I try to 
> 
> circumvent this by using ?NumberQ but without success. Please try the 
> 
> following toy example:
> 
> 
> 
> trial[a_?NumberQ] :=
> 
>      NDSolve[{ti'[t] == ti[t] , ti[0] == a} , ti, {t, 0, 10}];
> 
> NIntegrate[ (ti[5] /. trial[a]), {a, 0, 10}]
> 
> Plot[ (ti[5] /. trial[a]), {a, 0, 10}]
> 
> 
> 
> NIntegrate does not evaluate to a number and throws a warning, while I 
> 
> get a perfect plot from Plot.
> 
> 
> 
> Does anybody know what to do?
> 
> 
> 
> Cheers,
> 
> 
> 
> Paul
> 
> 


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