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Re: gauss chebychew quadrature in integration package


From: David Bateman
Subject: Re: gauss chebychew quadrature in integration package
Date: Mon, 23 Jun 2008 10:07:08 +0200
User-agent: Thunderbird 2.0.0.12 (X11/20080306)

Thomas Plehn wrote:
> http://img28.picoodle.com/img/img28/4/6/22/f_quadraturem_a5f90c3.png
>
> hello,
> I have tried to integrate a simple function in octave using the integration 
> package.
> the function is f(x,y)=x^2*sin(y)
> the integration limits for both x and y are from 0 to 1.
> the result should be (1-cos(1))/3 = 0,15323
> this result is yielded by quadndg, gquadnd
> but cquadnd yield a different result
>
> should this be considered as a bug? 
>
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> Help-octave mailing list
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>   
For what its worth, with 3.1.x (I.E. the head of the repository) and the
dblquad function I added I get

octave:1> dblquad (@(x,y) x.^2 .* sin (y), 0, 1, 0, 1, 1e-6, @quadgk)
ans =  0.15323
octave:2> dblquad (@(x,y) x.^2 .* sin (y), 0, 1, 0, 1, 1e-6, @quadv)
ans =  0.15323

Yes I suspect its a bug you found, though if you can look further at the
cquadnd function for bugs then that would help as I', not sure this will
be fixed otherwise.


D.


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David Bateman                                address@hidden
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