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Re: Integer

• To: mathgroup at smc.vnet.net
• Subject: [mg55788] Re: Integer
• From: Bill Rowe <readnewsciv at earthlink.net>
• Date: Wed, 6 Apr 2005 03:11:23 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

On 4/5/05 at 3:21 AM, flashlight at student.unibe.ch (Daniel Arnold)
wrote:

>How can I tell Mathematica that n is just an integer variable?

It would be helpful if you indicated how you are using n. A couple of possibilities come to mind.

One might be to create a function of n where n is an integer.

This could be done as

f[n_Integer]:=x^2

That is, I've defined f for integer values only. Any non-integer supplied to f will cause Mathematica to leave f as unevaluated since f is undefined for non-integer values.

Another might be in an expression. For example, Simplify[Sin[n Pi]] returns Sin[n Pi] since n could be any value. But Simplify[Sin[n Pi], Element[n, Integers]] returns 0 since Element[n, Integer] tells Mathematica n is an integer.
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