Re: How to find out the transformation used in Mathematica
- To: mathgroup at smc.vnet.net
- Subject: [mg51462] Re: How to find out the transformation used in Mathematica
- From: carlos at colorado.edu (Carlos Felippa)
- Date: Sun, 17 Oct 2004 21:49:58 -0400 (EDT)
- References: <ckt7jn$7cv$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Ann Lee <kan2 at rogers.com> wrote in message news:<ckt7jn$7cv$1 at smc.vnet.net>...
> Hi,
>
> I tried the following indefinite integral
>
> Integrate[Exp[-x^2/2]/(4 + x^2), {x, -Infinity, Infinity}]
>
> Mathematica gave me
>
> Pi*e^2*Erfc[Sqrt[2]]
>
> which is very nice. However, I don't know how Mathematica got
> this answer and would like to find out what kind of transformation
> that it uses to get this answer. Is there anyway for us to ask
> Mathematica to provide the transformation that it uses to arrive at
> this answer. Or alternatively, can anyone tell me how to get the
> integral above?
>
>
> Best,
>
> Ann
Storing tables is one way. That integral is 7.4.11 of Abramowitz and
Stegun (1964)
Some tables, e.g. Gradshteyn, now come in cdrom with the results
typeset-ready for cut & paste in TeX.