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Re: Placing the "&"

• To: mathgroup at smc.vnet.net
• Subject: [mg114857] Re: Placing the "&"
• From: Themis Matsoukas <tmatsoukas at me.com>
• Date: Mon, 20 Dec 2010 00:41:23 -0500 (EST)

Ziloo,

I am not sure what you mean by "once a pure function becomes an argument for another standard function [...]".  A pure function is the entire construct that includes # and ends with &. Maybe you are referring to the # as the pure function? That's only the placeholder for the dummy variable. For example, in

PrimeQ[2^(#)+1]&

the pure function is the entire line, not just the #. The above is equivalent to the standard function,

f[x_]:= PrimeQ[2^(x)+1]

Compare now PrimeQ[2^(#) + 1] &[2] and f[2]. They both evaluate the function at x=2 and give the same answer.

Does this help?

Themis