Re: Indefinite numbers of arguments in a function

*To*: mathgroup at smc.vnet.net*Subject*: [mg87848] Re: Indefinite numbers of arguments in a function*From*: Szabolcs <szhorvat at gmail.com>*Date*: Fri, 18 Apr 2008 07:11:00 -0400 (EDT)*References*: <fu9fnt$c91$1@smc.vnet.net>

On 18 Apr, 08:39, Patrick Klitzke <philologo... at gmx.de> 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. Search for patterns or pattern matching in the documentation. _ is a pattern that matches a single expression. __ can match one or more expressions: myPlus[args__] := Plus[args]