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Re: Integrate vs Nintegrate for impulsive functions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg61760] Re: Integrate vs Nintegrate for impulsive functions
  • From: Fred Bartoli <fred._canxxxel_this_bartoli at RemoveThatAlso_free.fr_AndThisToo>
  • Date: Fri, 28 Oct 2005 03:25:46 -0400 (EDT)
  • References: <djn3na$inr$1@smc.vnet.net>
  • Reply-to: Fred Bartoli <fred._canxxxel_this_bartoli at RemoveThatAlso_free.fr_AndThisToo>
  • Sender: owner-wri-mathgroup at wolfram.com

Try to evaluate the integral with symbolic coefficients.
It gives the same result as Nintegrate.

-- 
Thanks,
Fred.



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"Pratik Desai" <pdesai1 at umbc.edu> a écrit dans le message de
news:djn3na$inr$1 at smc.vnet.net...
> Hi Folks
>
>
> I have an expression resulting from a fourier series (for a 1D wave
> equation for a string) (fourier coeffficient) of the form
>
> h[x_]=(-0.24982234345508192 - 0.0429732983215806*I)*
>  Sin[(3.1734427242687215 + 0.3295480781081674*I)*x]*
>  (Cosh[1000.*(-0.4 + x)^2] - Sinh[1000.*(-0.4 + x)^2])
>
> I try to integrate this on the domain x(0,1) to get the fourier
> coefficient. I get some results that I need help explaining
>
>
> Integrate[h[x],{x,0,1}]
>
>  >>0+0 *I
>
> NIntegrate[h[x],{x,0,1}]
>
>  >>-0.0133612 - 0.00285551 \[ImaginaryI]
>
> Is the result from NIntegrate valid
>
> The initial condition is essentially a smoothed delta function at x=0.4
>
> gxx[x_]=E^(-1000.*(-0.4 + x)^2)
>
> Please advise
>
>
> Regards
>
>
> Pratik .
>
> -- 
> Pratik Desai
> Graduate Student
> UMBC
> Department of Mechanical Engineering
> Phone: 410 455 8134
>
>



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