# The Naked Scientists Forum

### Author Topic: What do you think tensor notation is?  (Read 1489 times)

#### Pmb

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##### What do you think tensor notation is?
« on: 10/02/2013 04:04:06 »
I'm curious about something. Elsewhere I asked what amounts to the question "What is tesor notation" and got no response. I finally found my answer in a text book I have but I'm curious as to what you folks think tensor notation is.
« Last Edit: 10/02/2013 15:46:26 by JP »

#### JP

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##### Re: What do you think tensor notation is?
« Reply #1 on: 10/02/2013 15:55:53 »
Pmb, I've edited your post to be a question, since we're trying to be better at enforcing our "posts must be phrased as questions rule."  If you'd prefer a different title, please do feel free to change it!

I think you'll get little response because tensor notation isn't commonly taught until upper level mathematics or physics courses, and we don't have a lot of folks who have had that kind of training.  I have learned a bit of it, and I know of two types of tensor notation.  The common one (that I learned in upper level coursework) is the index notation used in Ricci calculus.  I won't go into descriptions because I'd probably get some of it wrong at this point (I rarely use it), and there's already a nice description at Mathworld: http://mathworld.wolfram.com/Tensor.html
(As an aside, I'd highly recommend Mathworld to anyone needing a good mathematics resource but not wanting to shell out money for a physical book.)

The less common one (that I learned of in The Road to Reality by Roger Penrose rather than in school) is Penrose's graphical notation.  It seems to be notable enough to get cited on Wikipedia (but not on Mathworld):
http://en.wikipedia.org/wiki/Penrose_graphical_notation

#### CliffordK

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##### Re: What do you think tensor notation is?
« Reply #2 on: 10/02/2013 19:15:01 »
It appears to be related to linear algebra and polar coordinates.  However, it may actually primarily be used in Engineering and Architecture, where one would be most concerned with stresses on materials.  I don't believe I ran into it in college despite fairly broad coursework.

Perhaps I'll take a look as I've had a more recent interest in machining.

#### Pmb

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• Posts: 1838
• Physicist
##### Re: What do you think tensor notation is?
« Reply #3 on: 10/02/2013 21:59:51 »
Thanks everyone.

Tensor notation is defined as idex notation + the summation convention. I was surprised to hear that even though I've been using tensors and that notation for years. The reason I was surprised to see it defined as such (in the mathematical physics text by Boas) is that I used in long before I knew what a tensor was. It appears that I'm not the only one to have made this mistake.

Can't fool good ole JP though! :)

#### The Naked Scientists Forum

##### Re: What do you think tensor notation is?
« Reply #3 on: 10/02/2013 21:59:51 »