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Re: FindRoot and NIntegrate

  • To: mathgroup at smc.vnet.net
  • Subject: [mg81905] Re: FindRoot and NIntegrate
  • From: lhimon at gmail.com
  • Date: Sat, 6 Oct 2007 04:40:52 -0400 (EDT)
  • References: <fe4tfg$5h$1@smc.vnet.net>

On Oct 5, 4:43 am, mfed... at gmail.com wrote:
> Hi all,
>
> I have what is probably a very simple problem.  I want to find x which
> solves an equation of the form
>
> \integral f(x,y) dy = 0
>
> I have tried something along the lines of
>
> FindRoot[ NIntegrate[ f(x,y) , {y, -inf, inf} ], {x, x_0 } ]
>
> but it doesn't work ---- my theory being that NIntegrate tries to go
> ahead and do the numerical integration before it knows what x is equal
> to... which blows up  because the integrand is - as a function of x -
> non-numerical... Is there a way around this?  I'm sure there's some
> trivial modification I can make to get things working again.
>
> Thanks, in anticipation ---
> MF

i am also interested in this question.  does anyone know the answer?



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