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Re: Best syntax for derivative


Aaron Fude wrote:

> Thanks. That's cool. May I ask a follow up question?
>  
> What if I want to have  g=f^2?
>  
> Is there a similar alternative to
>  
> g[x_, y_, z_] := f[x, y, z]^2?
>  
> Thanks again!

The Derivative thing can work because the number of arguments it gets 
determines how many arguments f has. In your example this information is 
unavailable, so you'll need to use Slot objects to achieve the same effect:

g = f[##]^2&

Carl

>  
>
>
>  
> On Thu, Feb 12, 2009 at 10:23 AM, Carl Woll <carlw at wolfram.com 
> <mailto:carlw at wolfram.com>> wrote:
>
>     Aaron Fude wrote:
>
>         Hi,
>
>         Suppose I have a function of three variables
>
>         f[x_, y_, z_]:=Sin[x y z]
>
>         And I want to construct g[x, y, z] which is the partial
>         derivative of f
>         [] with respect to y. I do
>
>         f[x_, y_, z_] := Sin[x y z]
>         g[x_, y_, z_] := D[f[x, temp, z], temp] /. temp -> y
>
>         but I'm sure there is something better. Something along the
>         lines of
>
>         g = Partial[f, 2]
>
>         Many thanks in advance.
>
>         Aaron
>
>          
>
>     It's:
>
>     g = Derivative[0, 1, 0][f]
>
>     Carl Woll
>     Wolfram Research
>
>



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