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MathGroup Archive 2006

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RE: Product over an arbitrary index.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg68696] RE: [mg68683] Product over an arbitrary index.
  • From: "David Park" <djmp at earthlink.net>
  • Date: Thu, 17 Aug 2006 04:17:54 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

How do indexes enter into your expression? Do you mean f[i,j]? What exactly
is the definition of your product? Do you mean something like the following,
where I have set m = 5?

Times @@ Flatten[Outer[f[#1, #2] &, {1, 4, 3}, Range[5]]]
f[1, 1] f[1, 2] f[1, 3] f[1, 4] f[1, 5] f[3, 1] f[3, 2] f[3, 3] f[3, 4] f[3,
    5] f[4, 1] f[4, 2] f[4, 3] f[4, 4] f[4, 5]

The answer to the second question is yes, but it would be helpful if you
gave a specific example.

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/


From: quantieny at gmail.com [mailto:quantieny at gmail.com]
To: mathgroup at smc.vnet.net


I have a function f(x,y)   that I would like to compute the product
over indices i,j
where i goes from an arbitrary list {1,4,3}  and j goes 1 to m.

Is this possible in mathematica the function Product itself seems to
only work over a continous sequence and it is not clear how I can use
two set of indices.

Additionally can I specify the product over an intersection or
complement of a list?.

Thanks,
K Frou



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