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Re: Indefinite numbers of arguments in a function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg87852] Re: Indefinite numbers of arguments in a function
  • From: dh <dh at metrohm.ch>
  • Date: Fri, 18 Apr 2008 07:11:44 -0400 (EDT)
  • References: <fu9fnt$c91$1@smc.vnet.net>


Hi Patrick,

the magic word is: BlankSequence, written: __ (two underscores). 

Similar: BlankSequenceRepeated. Here is an example:

myPlus[x__]:=Plus[x]

hope this helps, Daniel





Patrick Klitzke wrote:

> Hello everybody,

> Is it possible to define a function in Mathematica, where the numbers of 

> arguments does not matter?

> 

> I know the function Plus is defined like that:

> 

> I call the function with two arguments( for example Plus[5,3]) or I can 

> call the function with five arguments (for example

> Plus[1,6,4,6,8]).

> 

> How can i define a function in Mathematica like that? I know I can 

> define for ever number of arguments a function like that:

> MyPlus[a_,b_]:=a+b

> MyPlus[a_,b_,c_]:=a+b+c

> MyPlus[a_,b_,c_,d_]:=a+b+c+d

> MyPlus[a_,b_,c_,d_,e_]:=a+b+c+d+e

> 

> I also know that I can create a list as one argument:

> 

> MyPlus[list_List] := (

>   m = 0; For[n = 1, n < Length[list] + 1, n++, m += list[[n]] ];

>   m

>    )

> 

> 

> But since there are functions like Plus, there has to be a way to define 

> those kind of functions.

> 

> I would be very glad, if someone could give me his advice.

> 

> Best regards,

> 

> Patrick Klitzke

> 

> email:   philologos14 at gmx.de

> 




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