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Re: evaluate f[{x,y,z}] when f[x,y,z] defined

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  • Subject: [mg103402] Re: [mg103383] evaluate f[{x,y,z}] when f[x,y,z] defined
  • From: "David Park" <djmpark at comcast.net>
  • Date: Sun, 20 Sep 2009 06:22:45 -0400 (EDT)
  • References: <1067475.1253352954604.JavaMail.root@n11>

f[x_, y_, z_] := Sqrt[x^2 + y^2 + z^2]
a = {4, 3, 2};

f @@ a
Sqrt[29]

But if it is something heavily used in both forms it might be worthwhile
making the extra definition.


David Park
djmpark at comcast.net
http://home.comcast.net/~djmpark/  



From: Murray Eisenberg [mailto:murray at math.umass.edu] 

I ought to know how to do this (simply) but don't, or at least don't 
recall how...

Often I have a function of several variables defined, for example:

   f[x_, y_, z_] := Sqrt[x^2 + y^2 + z^2]

And I have some list of numbers, e.g.:

   a = {4, 3, 2};

How can I evaluate the following...

   f[a]

... without having to make a separate definition such as

   f[{x_, y_, z_}] := f[x, y,z]

?

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305




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