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Re: Some assistance from seasoned users.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124909] Re: Some assistance from seasoned users.
  • From: "djmpark" <djmpark at comcast.net>
  • Date: Sun, 12 Feb 2012 04:58:55 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <13610289.2905.1328961103252.JavaMail.root@m06>

Peter,

Probably because you are not using proper Mathematica syntax. Mathematica
symbols all begin with a capital letter. Infinity could be typed in just as
the plain word Infinity. Esc inf  esc can be used to type in the equivalent
infinity symbol. Similarly pi can be typed in as the word Pi. The Greek
symbol can be entered with esc p esc.

Integrate[Sin[x]/x, {x, 0, \[Infinity]}] 
\[Pi]/2 

Integrate[Sin[x]^3/x, {x, 0, \[Infinity]}] 
\[Pi]/4 

Integrate[Sin[x]^3/x^3, {x, 0, \[Infinity]}] 
(3 \[Pi])/8 

You could copy and paste those back into your Mathematica notebook to check
them. To post to MathGroup you could select and Copy As Input Text (from the
right click context menu) and then paste into the posting. Then responders
could see the exact statement you tried to use and usually give move
specific answers.

A more specific or indicative Subject heading might also help other readers
of the group to obtain answers. Something like: "Integrals fail to properly
evaluate"


David Park
djmpark at comcast.net 
http://home.comcast.net/~djmpark/index.html 





From: peter livingston [mailto:peter.livingston at cox.net] 

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




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