[scilab-Users] Re: intg: results differ substantially from those from Wolfram Alpha, which are correct?

[Sylvestre Ledru]

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S

Le vendredi 20 mai 2011 à 06:09 -0700, Bassam Awad a écrit :
> Any one knows how to unsubscribe to the list?
> 
> 
> 
> --- On Fri, 5/20/11, Jean-Yves Baudais
> <jean-yves.baudais at insa-rennes.fr> wrote:
>         
>         From: Jean-Yves Baudais <jean-yves.baudais at insa-rennes.fr>
>         Subject: Re: [scilab-Users] Re: intg: results differ
>         substantially from those from Wolfram Alpha, which are
>         correct?
>         To: users at lists.scilab.org
>         Date: Friday, May 20, 2011, 1:05 PM
>         
>         Hello,
>         
>         > ok, for normal distribution I found a cure - folded normal
>         dist (
>         > http://en.wikipedia.org/wiki/Folded_normal_distribution)
>         that avoids the
>         > abs() in the integral; but what about other cases?
>         
>           But in the folded normal dist there is no log function as in
>         your function. Your problem is the same as
>         
>         --> function y=f(x),y=exp(-x), endfunction
>         --> intg(0,1e10,f)
>         ans=
>         0
>         
>         The integral calculation is performed with Monte-Carlo method
>         (I think), so the probability to obtain non zero contribution,
>         when the upper limit increases, decreases. With lower upper
>         limit the result is good
>         
>         --> intg(0,1e2,f)
>         ans=
>         1
>         
>         When lim(x->0) f(x)=0, you must pay attention to the upper
>         limit. It is your case.
>