Re: Some assistance from seasoned users.

*To*: mathgroup at smc.vnet.net*Subject*: [mg124933] Re: Some assistance from seasoned users.*From*: David Bailey <dave at removedbailey.co.uk>*Date*: Mon, 13 Feb 2012 03:38:07 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <jh6k2n$jr9$1@smc.vnet.net>

On 11/02/2012 20:46, peter livingston wrote: > Folks! > > > > I have recently come to the pleasures of Mathematica from other popular but > very expensive programming methods that I, as a retiree, cannot afford. > > > > My specific question is this: why am I able to get Mathematica to do the > complete integral of sin(x)/x, but it refuses to do any of the other types: > specifically sin^3[x]/x or sin^3[x]/x^3 over the half interval from zero to > infinity. (see page 449 of G& R Table of Integrals). > > > > It seems to suggest that throwing away my Gradshtein and Ryzhik is premature > in spite of the claims in the Mathematica "Mathematics and Algorithms" > manual. > > > > Peter Livingston All of those integrals evaluate, but you have to use Sin - not sin. All the built-in keywords start with a capital letter, and conversely if you use a variable that starts in lower case, you can be sure it is 'yours'. BTW, no error is generated, because Mathematica treats your input (with sin) exactly as it would the integral of f[x]/x^3 - as something that might evaluate later if f is subsequently defined. David Bailey http://www.dbaileyconsultancy.co.uk