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ps: I have asked this question on https://tex.stackexchange.com/ (here) but is regarded as off-topic. So I moved it here.

I have seen different ways in papers to put comma after equation.

  1. right after the equation:

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  2. right before where:

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  3. no comma at all:

    enter image description here

Which way should I choose? Which way is more standard?

Community
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herohuyongtao
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1 Answers1

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The first variant is correct (though this is a question on typography rather than math). More precisely, if you would place a comma with non-display formulas (or if the formula where a normal sequene of words) the you also should place a comma with a display formula. The same holds for periods. However, in TeX you would set the comma or other interpunction after the single dollar ("$a=b$, where"), but before the double-dollar ("$$a=b,$$ where") for the very reason that variant two must be avoided. Sometimes switching from inline to display causes variant two by mistake.

Hagen von Eitzen
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  • What about the other two? Are they both wrong? – herohuyongtao Jan 16 '14 at 10:39
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    Variant 2 is quite horrible. I often end up using variant 3 myself, but technically, one should have a comma somewhere. – Tobias Kildetoft Jan 16 '14 at 10:44
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    Variant 2 is really wrong as far as the term wrong applies to this kind of question. For variant 3 I must admit that the most prominent rule on English commas that I know is "If in doubt leave it out". But I guess there is a semantic difference between having a comma before "where" or not. I suggest to cross-check at http://english.stackexchange.com – Hagen von Eitzen Jan 16 '14 at 11:13