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Re: a few questions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg27926] Re: a few questions
  • From: "Paul Lutus" <nospam at nosite.com>
  • Date: Sat, 24 Mar 2001 00:48:53 -0500 (EST)
  • References: <99f5km$bfk@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

"Tomaz Cedilnik" <tcedilnik at ntlworld.com> wrote in message
news:99f5km$bfk at smc.vnet.net...
> I'm editing some .m files but I currently can't access a working copy of
> Mathematica so I need help.
>
> 1) Are the funkcions to tell whether the argument is a number/list,
> NumberQ and ListQ?
>
> 2) How do you get the header ( a[b,c] ---> a ) ?
>
> 3) Does Join work like that:
> Join[{1,2,3},4,{5},{6,{7,8}},9] -> {1,2,3,4,5,6,{7,8},9}
> or do all arguments have to be lists?
>
> 4) If I define
> f[x_,y_:Null] := g[x,y]
> does it work like this:
> f[1,2] -> g[1,2]
> f[3]   -> g[3]   ?
>
> 5) Which function returns position of the element in the list?
> Pos[list,element]?
>
> 6) How to replace a sub-list, e.g.:
> {a,b,c,d,e,f,g,h} 3 {X,Y,Z}  --->  {a,b,X,Y,Z,f,g,h}
>
> 7) What are Array, Scan, Function, Take, FoldList, Append, NestList?
> My guesses:
> Array[f,n] -> {f[1],f[2],...,f[n]}
> Scan[f,{a,b,c,d,e}] -> f[a];f[b];f[c];f[d];f[e]

A little friendly advice. You have no chance of interpreting anything more
than a trivial Mathematica file without testing it with Mathematica and
drawing conclusions based on the tests.

--
Paul Lutus
www.arachnoid.com





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