Re: Permutation Tensor

Date	2012-07-05 11:25 +0200
From	"A. K." <akk@nospam.org>
Newsgroups	comp.lang.forth
Subject	Re: Permutation Tensor
References	<jt3erh$cd2$1@dont-email.me> <4ff5412d$0$6635$9b4e6d93@newsspool2.arcor-online.net> <jt3k24$70o$1@dont-email.me>
Message-ID	<4ff55d72$0$6641$9b4e6d93@newsspool2.arcor-online.net> (permalink)
Organization	Arcor

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On 05.07.2012 10:42, Arnold Doray wrote:
> On Thu, 05 Jul 2012 09:25:07 +0200, A. K. wrote:
>
>> On 05.07.2012 09:13, Arnold Doray wrote:
>>> What's the best way to implement the 3D permutation tensor E(I,J,K)?
>>>
>>> Thanks,
>>> Arnold
>>>
>>>
>> There is no generic answer to your question.
>> It really depends on - which planes you need most - whether you use
>> another library - whether you intend to use the GPU - which tensor
>> elements you access mostly etc etc
>
> No, I mean the *permutation* tensor... not tensors in general.
>
> Given I, J, K on the stack, return the -1, 1 or 0.
>
> -AD
>

How about
( i j k --> n ) 10 * + 10 * +
then CASEs
n = 123 or 312 or 231 --> eps = 1
n = 132 or 321 or 213 --> eps = -1
otherwise --> eps = 0

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Permutation Tensor Arnold Doray <invalid@invalid.com> - 2012-07-05 07:13 +0000
  Re: Permutation Tensor "A. K." <akk@nospam.org> - 2012-07-05 09:25 +0200
    Re: Permutation Tensor Arnold Doray <invalid@invalid.com> - 2012-07-05 08:42 +0000
      Re: Permutation Tensor "A. K." <akk@nospam.org> - 2012-07-05 11:25 +0200
        Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-06 18:49 -0700
          Re: Permutation Tensor mhx@iae.nl (Marcel Hendrix) - 2012-07-07 08:32 +0200
            Re: Permutation Tensor "A. K." <akk@nospam.org> - 2012-07-07 09:49 +0200
            Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-07 05:35 -0700
               Re: Permutation Tensor mhx@iae.nl (Marcel Hendrix) - 2012-07-07 15:45 +0200
                Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-07 07:32 -0700
                Re: Permutation Tensor mhx@iae.nl (Marcel Hendrix) - 2012-07-07 17:53 +0200
                Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-07 09:10 -0700
                Re: Permutation Tensor mhx@iae.nl (Marcel Hendrix) - 2012-07-07 18:41 +0200
                Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-07 12:24 -0700
                Re: Permutation Tensor Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2012-07-08 07:48 +0100
                Re: Permutation Tensor Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2012-07-08 08:09 +0100
                Re: Permutation Tensor mhx@iae.nl (Marcel Hendrix) - 2012-07-08 09:23 +0200
                Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-08 05:55 -0700
                Re: Permutation Tensor Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2012-07-08 20:14 +0100
                Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-08 13:49 -0700
                Re: Permutation Tensor Paul Rubin <no.email@nospam.invalid> - 2012-07-07 13:03 -0700
                Re: Permutation Tensor mhx@iae.nl (Marcel Hendrix) - 2012-07-07 23:54 +0200
                Re: Permutation Tensor Paul Rubin <no.email@nospam.invalid> - 2012-07-07 16:43 -0700
                Re: Permutation Tensor mhx@iae.nl (Marcel Hendrix) - 2012-07-08 09:07 +0200
                Re: Permutation Tensor Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-08 13:03 +0000
                Re: Permutation Tensor anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-09 14:50 +0000
                Re: Permutation Tensor m.a.m.hendrix@tue.nl - 2012-07-10 00:28 -0700
                Re: Permutation Tensor anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-10 10:11 +0000
                Re: Permutation Tensor mhx@iae.nl (Marcel Hendrix) - 2012-07-10 21:37 +0200
                Re: Permutation Tensor anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-07-11 13:50 +0000
                Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-10 05:10 -0700
        Re: Permutation Tensor Paul Rubin <no.email@nospam.invalid> - 2012-07-06 20:46 -0700
          Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-07 05:36 -0700
  Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-06 18:18 -0700
    Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-06 18:33 -0700
    Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-07 07:28 -0700
      Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-07 08:02 -0700
  Re: Permutation Tensor Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-07 19:58 +0000
    Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-08 05:45 -0700
      Re: Permutation Tensor Albert van der Horst <albert@spenarnc.xs4all.nl> - 2012-07-08 20:05 +0000
  Re: Permutation Tensor awegel@arcor.de (Alex Wegel) - 2012-07-08 14:24 +0200
    Re: Permutation Tensor awegel@arcor.de (Alex Wegel) - 2012-07-11 07:09 +0200
      Re: Permutation Tensor awegel@arcor.de (Alex Wegel) - 2012-07-11 18:42 +0200
        Re: Permutation Tensor mhx@iae.nl (Marcel Hendrix) - 2012-07-11 20:18 +0200
          Re: Permutation Tensor awegel@arcor.de (Alex Wegel) - 2012-07-12 12:43 +0200
  Re: Permutation Tensor awegel@arcor.de (Alex Wegel) - 2012-07-08 23:44 +0200
    Re: Permutation Tensor Krishna Myneni <krishna.myneni@ccreweb.org> - 2012-07-10 17:06 -0700
      Re: Permutation Tensor awegel@arcor.de (Alex Wegel) - 2012-07-11 07:09 +0200

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