Re: Two related question. Question 1

*To*: mathgroup at smc.vnet.net*Subject*: [mg57513] Re: [mg57498] Two related question. Question 1*From*: Andrzej Kozlowski <andrzej at akikoz.net>*Date*: Tue, 31 May 2005 04:59:04 -0400 (EDT)*References*: <200505300100.VAA26808@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On 30 May 2005, at 10:00, Kazimir wrote: > *This message was transferred with a trial version of CommuniGate > (tm) Pro* > 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 > > Just evaluate: Unprotect[Times, Plus, Power]; (a_?NumericQ*f_.)[x__] := a f[x]; (f_ + g_)[x__] := f[x] + g[x]; (f_*g_)[x__] := f[x]*g[x]; (f_^n_?NumericQ)[x__] := f[x]^n Protect[Times, Plus, Power]; and then proceed as in your message. Everything will work the way you expect. Andrzej Kozlowski

**References**:**Two related question. Question 1***From:*kazimir04@yahoo.co.uk (Kazimir)