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MathGroup Archive 2004

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Re: Functions with optional parameters

  • To: mathgroup at smc.vnet.net
  • Subject: [mg51921] Re: Functions with optional parameters
  • From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
  • Date: Fri, 5 Nov 2004 02:17:15 -0500 (EST)
  • Organization: Uni Leipzig
  • References: <cmclfa$i7s$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

a)
addThem[a_, b_, c_:Undefined] := If[Undefined === c, a + b, a + b + c]

b)

addThem[a__] := Plus[a]

Regards
  Jens

"Gregory Lypny" <gregory.lypny at videotron.ca> schrieb im Newsbeitrag 
news:cmclfa$i7s$1 at smc.vnet.net...
> Hello everyone,
>
> How can I create functions with optional parameters?  For example, a
> simple function to add two or three numbers:
>
> addThem[a_,b_,c_]:=If[c is not empty, Sum[a,b,c],Sum[a,b]]
>
> I'm not sure of the proper syntax to test whether c is null or empty.
>
> Greg
> 



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