How to find out the transformation used in Mathematica

*To*: mathgroup at smc.vnet.net*Subject*: [mg51446] How to find out the transformation used in Mathematica*From*: Ann Lee <kan2 at rogers.com>*Date*: Sun, 17 Oct 2004 03:06:31 -0400 (EDT)*Reply-to*: kan2 at rogers.com*Sender*: owner-wri-mathgroup at wolfram.com

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