Re: Two related question. Question 1
- To: mathgroup at smc.vnet.net
- Subject: [mg57538] Re: Two related question. Question 1
- From: David Bailey <dave at Remove_Thisdbailey.co.uk>
- Date: Tue, 31 May 2005 05:00:41 -0400 (EDT)
- References: <d7dp2r$qam$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
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[11]:=
> Derivative[1][f]
>
> Out[11]=
> 2 #1&
>
> In[12]:=
> Derivative[2][f]
>
> Out[12]=
> 2&
>
> Regards
>
> Vlad
>
Vlad,
Look at your pure function in FullForm, and the answer is more or less
obvious:
Function[Plus[Power[Slot[1],2],Slot[2]]]
For example:
g=With[{ff=f[[1]]^2},Function[ff]]
Note however that Function can have several arguments, which would
require some more general code.
David Bailey
http://www.dbaileyconsultancy.co.uk