Re: Functions with optional parameters
- To: mathgroup at smc.vnet.net
- Subject: [mg51945] Re: [mg51886] Functions with optional parameters
- From: "David Park" <djmp at earthlink.net>
- Date: Fri, 5 Nov 2004 02:18:46 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Gregory, Look up Section 2.3.9, Optional and default arguments in The Mathematica Book, available in Help. addThem[a_, b_, c_:0] := a + b + c addThem[1, 2] 3 addThem[1, 2, 3] 6 Of course, there are easier ways to add a variable length list of numbers so another example might be more instructive. How about... combindThem[a_, b_, opt_:Plus] := a~opt~b combindThem[a, b] a + b combindThem[a, b, Times] a b combindThem[a, b, Power] a^b combindThem[a, b, #1^2 + #2^2 & ] a^2 + b^2 David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ From: Gregory Lypny [mailto:gregory.lypny at videotron.ca] To: mathgroup 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