intg: results differ substantially from those from Wolfram Alpha, which are correct?

[Ginters Bušs]

On Fri, May 20, 2011 at 2:09 PM, Ginters Bušs <ginters.buss at gmail.com>wrote:

> 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.
>
> Pardon, Wolfram alpha gives -0.005; if the 2nd argument 0.1 is increase to
0.4, then intg gives 1.555D-47, and Wolfram Alpha gives -0.111, the
difference increases.
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