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.