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## RE: 3D array

**From**: |
John W. Eaton |

**Subject**: |
RE: 3D array |

**Date**: |
Tue, 13 Nov 2001 19:28:58 -0600 |

On 13-Nov-2001, address@hidden <address@hidden> wrote:
| Out of interest, how should arithmetic on N dim arrays
| be defined?
I'm no expert, but element-by-element operations seem straightforward
to me. I suppose there are other things that make sense for tensors.
At least a generalized inner product, which Matlab seems to have under
the name times, but not for the operator *. Odd.
As for things like
svd (some_Nd_matrix);
your guess is as good as mine (and why I would vote for leaving it
undefined in Octave).
| I haven't used N dim arrays in Matlab. For those who have:
| Is that Matlab implementation well thought out?
| Or are there inconsistencies and ambiguities (as is
| fairly common in some of the worse thought out parts of
| Matlab syntax)?
Well, it is apparently impossible to enter an N-d matrix directly
using the "[...]" syntax because of the historical interpretation of
things like
[[1, 2; 3, 4], [5, 6; 7 8]]
(In Mathematica, I think you would use
{{{1, 2}, {3, 4}}, {{5, 6}, {7, 8}}}
though I tend to become confused about what is a row and what is a
column...)
jwe
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**3D array**, *Laurent Jacques*, `2001/11/13`
**RE: 3D array**, *Ted Harding*, `2001/11/13`
**RE: 3D array**, *John W. Eaton*, `2001/11/13`
**RE: 3D array**, *adler*, `2001/11/13`
**RE: 3D array**,
*John W. Eaton* **<=**
**RE: 3D array**, *adler*, `2001/11/15`
**Re: 3D array**, *Paul Kienzle*, `2001/11/16`
**Re: 3D array**, *John W. Eaton*, `2001/11/16`
**Re: 3D array**, *Laurent Jacques*, `2001/11/14`
**Re: 3D array**, *Laurent Jacques*, `2001/11/14`