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Re: arguments/realtime3d

  • To: mathgroup at
  • Subject: [mg32302] Re: arguments/realtime3d
  • From: "daniel" <6.6e-34 at>
  • Date: Sat, 12 Jan 2002 05:18:12 -0500 (EST)
  • Organization: Technical University Berlin, Germany
  • References: <a1mbn7$2t4$>
  • Sender: owner-wri-mathgroup at

> In[1]:= g[x___?OptionQ] := Print["Number of arguments: ", Length[{x}]]
> In[2]:= g[a -> b, c -> d, e -> f]
> Number of arguments: 3
> Why would one create a function with only optional arguments in the first
> place?  Do you intend a Null argument to be valid input as well?
Yes, I want the function to accept a null argument.
The function is a constructor for a simulation starting set, it returns a
list of system parameters.
My concern about Length[x] was what occurs if f is called without an
argument and x has been defined
elsewhere. Is this safe even for older versions of Mathematica?

Thanks for your answer


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