       Re: Two related question. Question 1

• To: mathgroup at smc.vnet.net
• Subject: [mg57508] Re: Two related question. Question 1
• From: Mark Fisher <mark at markfisher.net>
• Date: Tue, 31 May 2005 04:58:59 -0400 (EDT)
• References: <d7dp2r\$qam\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Is this what you're looking for?

f = #1^2 + #2 &
c = Composition[#^2 &, f]

Derivative[2,0][c]

--Mark.

Kazimir wrote:
> I have two related question. Let me introduce a pure function
>
> f = #1^2 + #2 &
>
> Now. I want to make an operation over the function, for example to
> find its square and to call the result (the expected function f = (#1^2
> + #2)^2 & ) c:
>
> c=f^2
>
> However, I do not obtain this, as
>
> c[a,b]
>
> does not evaluate to (a+b)^2. Can anybody advise me how to obtain
> such a function without long substitutions. I would like to obtain
> something which is made for derivatives :
>
> In:=
> Derivative[f]
>
> Out=
> 2 #1&
>
> In:=
> Derivative[f]
>
> Out=
> 2&
>
> Regards
>