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

[Samuel GOUGEON]

  Hello,
The following thread on Bugzilla may also feed the present discussion:
http://bugzilla.scilab.org/show_bug.cgi?id=5728
Regards
Samuel

----- Message d'origine -----
De : Ginters Bušs
Date : 20/05/2011 13:09:
> Dear all,
>
> Let's integrate:
>
> function y=f(x, a, 
> sigma),y=(1/sqrt(2*%pi))*log(abs(a+sigma*x))*exp(-(x^2)/2),endfunction
>
> out=intg(-1e+2,1e+2,list(f,1,.1))
>
> out=8.605D-49
>
> but Wolfram Alpha gives out= -0.111
>
> which is a totally different answer.
>
> I've noticed that intg and integrate incline to give values close to zero when 
> boundaries tend to infinity. So, I trust Wolfram Alpha more. How to get around 
> the apparent mistakes in intg, integrate (particularly, I'm interested in 
> indefinite integrals)?
>
> Gin.
>
>