Services & ResourcesWolfram ForumsMathGroup Archive

[Date Index] [Thread Index] [Author Index]

case differentiation problem with "Assumptions"

• To: mathgroup at smc.vnet.net
• Subject: [mg83652] case differentiation problem with "Assumptions"
• From: Paul.Wenk at googlemail.com
• Date: Tue, 27 Nov 2007 06:14:39 -0500 (EST)

Hello,
I found the following problem using $Assumptions:
Let us calculate the integral: Integrate[Cos[(n \[Pi] (-W + y))/(2
W)]^2/W,{y,-W,W}]
for n \[Element] Integers and n>0 you receive 1, for n=0 you receive
2.
If you make the assumption
$Assumptions = n \[Element] Integers
then you get for the above integral the output 1, although for n=0
(also integer) it should be 2!
Why mathematica is not using a case differentiation in this case? How
is the information about the integer element inserted?

cheers,
Paul

p.s.
I'm using Mathematica 6.0.0 on Linux x86

• Follow-Ups:
  • Re: case differentiation problem with "Assumptions"
    • From: Daniel Lichtblau <danl@wolfram.com>