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MathGroup Archive 2005

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Re: NIntegrate with Minimize

  • To: mathgroup at smc.vnet.net
  • Subject: [mg53556] Re: [mg53549] NIntegrate with Minimize
  • From: "Oz" <x_download at hotmail.com>
  • Date: Tue, 18 Jan 2005 05:07:55 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Woops, sorry. The code is

ff[a_] := First[Minimize[{x + a, 0 <= x <= 2}, {x}]]
NIntegrate[ff[a], {a, 0, 6}]

and the problem is that it can't do the Minimize symbolically, which it
seems to try to do before putting the value of 'a' in.

I have, since posting, found out a way to work around it (thanks to Andrzej
Kozlowski), namely putting in ?NumericQ next to the variable in the function
definition: 

ff[a_?NumericQ] := First[Minimize[{x + a, 0 <= x <= 2}, {x}]]
NIntegrate[ff[a], {a, 0, 6}]

18.

Kind Regards,
Oz

-----Original Message-----
From: DrBob [mailto:drbob at bigfoot.com] 
To: mathgroup at smc.vnet.net
Subject: [mg53556] Re: [mg53549] NIntegrate with Minimize

Try posting that in InputForm, so that we can see the code.

http://www.eclecticdreams.net/DrBob/copy_as_inputform.htm

Bobby

On Sun, 16 Jan 2005 22:24:06 -0500 (EST), Oz <x_download at hotmail.com> wrote:

> Hiya,
>
> I'm having trouble performing a numerical integration that involves a
> Minimize. I think it might have something to do with HoldAll, but am not
> sure how to fix it (couldn't find any actual solutions that worked in
> the archives). Any help most appreciated. Here is a simplified version
> of the code (the function and constraints I'm actually using are more
> complicated):
>
> ff[a_] := First[Minimize[{x + a, 0 â?¤ x â?¤ 2}, {x}]]
> NIntegrate[ff[a], {a, 0, 6}]
>
> Mathematica raises a Minimize::objv error, complaining that a+x contains
> a nonconstant expression independent of x, and so the NIntegrate fails.
> Ideas?
>
> Thanks,
> Oz
>
>
>
>
>



-- 
DrBob at bigfoot.com
www.eclecticdreams.net


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