Re: Functions with optional parameters
- To: mathgroup at smc.vnet.net
- Subject: [mg51929] Re: Functions with optional parameters
- From: Curt Fischer <crf3 at po.cwru.edu>
- Date: Fri, 5 Nov 2004 02:17:34 -0500 (EST)
- References: <cmclfa$i7s$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Gregory Lypny wrote: > 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. Hi Greg, Here is code I copied from the Mathematica 5.0.1 Help Browser, which I got from looking up BlankNullSequence (___). In[1]:= f[x_,y___]:=x+y In[2]:= f[a,b,c,d] Out[2]= a+b+c+d In[3]:= f[a] Out[3]= a -- Curt Fischer