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$ x_{i,j}^{ k}$

May I say the following to say the above notation?

x sub i j to k ?

x sub i j sup(prounced like "soup") k ? (Can I say "soup" for "superscript"?

Could you please show me a proper way to say the above notation?

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You could just... not? If you're talking to someone about tensors with $3$ indices it's probably time to break out the paper or chalkboards. – Qiaochu Yuan Jul 28 '12 at 23:15
@everyone I've created the tag pronunciation. Please let me know if this a bad idea. – user2468 Jul 28 '12 at 23:16
There might be something useful in the references in the previous question, Is there a definitive guide to speaking mathematics? – Rahul Jul 28 '12 at 23:23
@RahulNarain, Thank you for the very useful reference!! – Tony Jul 28 '12 at 23:31
I would avoid saying "sup" and use "super" if needed (sub/super are both Latin prefixes), and I think "sup" might be easily heard as "sub". – Andrew Jul 29 '12 at 2:01

3 Answers 3

up vote 4 down vote accepted

IMHO: If all of the items have the same sub/super script structure (such as tensors with the same index patterns), then I don't see any harm in saying the indeces without saying "sub" or "sup". For example, I'd say "$x$ $i$ $j$ $k$" for $x_{i,j}^k$. In lectures, this works out just fine, especially when accompanied by the symbol $x_{i,j}^k$ on the board.

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Thank you very much. That's a great tip!! – Tony Jul 29 '12 at 8:14
@Andrew, Thank you for your advice!! – Tony Jul 29 '12 at 8:16

As long as you're understood I don't think there's a proper way. I would say "soup" or "super" and I am a native English speaker.

But there may also be a different way to talk about it (e.g., "All the upper indices do X" or "Those dimensions vanish") depending on your final message.

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If the superscript $k$ is an exponent and $i,j$ are indices, I would say "x sub i j to the k", or even "x i j to the k", or least ambiguously "the k'th power of x sub i j". If $x_{i,j}^{k}$ has some other meaning then "x sub i j sup k" is a fine way to refer to how the expression is written but I would prefer the other phrase when raising $x_{i,j}$ to the power of $k$ is what is meant.

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