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MathGroup Archive 2004

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Re: a strange line of code

  • To: mathgroup at smc.vnet.net
  • Subject: [mg52737] Re: [mg52710] a strange line of code
  • From: "Caffa Vittorio Dr." <Caffa at iabg.de>
  • Date: Sat, 11 Dec 2004 05:21:53 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Try this:

In[1]:= f[x]

Out[1]= f[x]

In[2]:= f@x

Out[2]= f[x]

In[3]:= x//f

Out[3]= f[x]

In[4]:= ?#
# represents the first argument supplied to a pure function. #n
represents the nth argument.

In[5]:= ?&
Function[body] or body& is a pure function. The formal parameters are #
(or #1), #2, etc. Function[x, body] is a pure function with a single
formal parameter x. Function[{x1, x2, ... }, body] is a pure function
with a list of formal parameters.

Cheers, Vittorio


-----Original Message-----
From: Stefan Schuster
To: mathgroup at smc.vnet.net
[mailto:bi1169*delete_from_star_to_star* at fh-weihenstephan.de] 
Subject: [mg52737] [mg52710] a strange line of code

Hello,

in a notebook, I found and function to calculate the Feigenbaum 
bifurcation Diagram.
I principial understand the Feigenbaum, and I think I'm also able to 
write such an funcion by myself, but not in this compact way.

Can someone please explain me the meaning of the Symbols #, @ and &

Here is the Code:

Feigenbaum = Compile[{{
     ?, _Real}}, ({?, #} &) /@ Union[Drop[NestList[
       ? # (1 - #) &, 0.2, 300], 100]]];

thanks in advance

Stefan


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