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Re: How to use "Apply" to do differentiation ?

• To: mathgroup at smc.vnet.net
• Subject: [mg114511] Re: How to use "Apply" to do differentiation ?
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Sun, 5 Dec 2010 21:59:16 -0500 (EST)

x^5//FullForm

Power[x,5]

Apply did what it is supposed to do, it replaced Power with D[#,x]&

Use

D[#,x]&[x^5]

5*x^4


See

 http://reference.wolfram.com/mathematica/ref/Function.html


Bob Hanlon

---- Mayasky <alix.zhang at gmail.com> wrote: 

=============
Something simple yet unbelievable occurred when I use:

Apply[D[#, x] &, x^5]

The output is invariably 1 whether I use x^5 or x^100.
Also I suggest you to try "Trace" command to see
the weirdness -- the output is messy if pasted as
text here.

Finally I have to take a detour and use:
Nest[D[#, x] &, x^5, 1]

I have been using Mathematica for several years and
never found that. I myself is wordless, but can anyone
explain that?