# MathJax Style: It is acceptable to include a period at the end of a block formula?

Is it acceptable practice to terminate a block formula with a period like this...

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Pellentesque blandit arcu orci, gravida accumsan sem tristique nec. Fusce luctus erat eu vulputate fermentum. Ut vulputate urna non magna dictum interdum. Nulla pretium nec magna at luctus. Quisque a odio ac justo viverra sodales. Curabitur sodales diam non purus finibus ullamcorper. Vestibulum quis libero vitae lacus commodo volutpat id vel metus. Phasellus id facilisis lorem. Mauris interdum purus ac elit ultrices molestie. Etiam ornare consectetur sem

$$01011000\phantom{2}10101000\phantom{2}00010010.$$

Etiam aliquet nisl eu lobortis semper. Vivamus quis augue purus. In nisi elit, volutpat at quam gravida, pulvinar dignissim libero. Nullam id auctor libero. Etiam congue ultricies eleifend. Suspendisse tincidunt rutrum tellus, id blandit mauris sodales ut. Aenean at justo et tortor pretium feugiat. Phasellus aliquet ut orci sit amet maximus. Nullam vitae ultrices arcu.

The intention is that the binary number is referred to by the "Etiam ornare consectetur sem" text preceding it. Semantically, they're part of the same sentence. The binary number effectively "ending" the sentence. They just happen to be split over two lines; for whatever reason.

I know that there's always the simple option of in-lining the binary number. And be done with it. I'm just wondering whether the above option with the period in the block formula is acceptable or discouraged in common practice. And on what grounds?

Note: For the avoidance of any confusion: That's a plain old sentence-ending period at the end of that binary number; not a radix point.

• I would say that you can either include a period in formula or just omit the period. Both are common and which you use is a matter of personal preference IMO. – Qudit Nov 10 '17 at 3:55
• I've seen people go either way too, so go with whatever you're comfy with. (Personally: I omit the period, but (often) include the question mark, and avoid the exclamation point lest the expression be misinterpreted as a factorial.) – J. M. is a poor mathematician Nov 10 '17 at 5:24
• I typically omit the period, even when the formula completes a sentence begun at the finish of the paragraph above it (but usually put a colon at the end of that paragraph to indicate the connection of thought), but in cases where the formula (displaystyle) includes text (words such as "whenever" or "unless", etc.) then I'm apt to use a period to terminate that formula. – hardmath Nov 10 '17 at 5:30
• I generally include punctuation in my formulas. Just like I would with inline mathematics that would have a comma after the formula (usually). – Asaf Karagila Nov 10 '17 at 8:02
• When writing mathematics in formal documents (I do this a lot when I write up patent applications for my clients) I insist on proper punctuation. This includes periods and commas because an equation may represent a complete sentence or a clause. An expression, in contrast (one lacking an equal sign or an inequality symbol or other abstract relational indicator) is not a complete sentence but still may require punctuation as need be. – Ron Gordon Nov 10 '17 at 11:58
• Is this really a meta question? I've often considered the same question for arbitrary math writing :) – apnorton Nov 14 '17 at 5:04
• Maths equations form part of a sentence -- it's possible that signs may be used for verbs, eg "we have $a = b$" is "we have $a$ equals $b$" -- and hence, just like usual writing, should have proper punctuation, eg full stops, commas and semi-colons. I do agree about avoiding exclamation marks though; the same for colons and brackets. Brackets ending in a maths display are quite unclear, I feel! – Sam T Nov 14 '17 at 22:06

It is generally encouraged to include punctuation in this case. See this question on the English language stackexchange, which contains a reference to wikipedia, stating explicitly that displayed formulae should include proper punctuation. See these two questions on the tex stackexchange for further confirmation.

• Mathematical text consists of sentences, and the various formulas are parts of those sentences. It would be confusing not to punctuate properly when punctuation would happen to come at the end of an inline formula. – Joonas Ilmavirta Nov 11 '17 at 15:37
• Somebody else offline pointed me to this 'Periods and commas in mathematical writing' discussion over at mathoverflow. It's interesting. Before asking this question, I had only ever seen a period in a block formula once. Now, I'm noticing it in several math-related things I've look at since. Isn't it funny how that happens? – algoHolic Nov 11 '17 at 18:39

Lately I have been putting in some blank space as 00010010 \; \; . $$00010010 \; \; .$$ This still gives the idea of ending a sentence, but the separation discourages the impression that the punctuation could be part of the mathematics.

The Latin above seems to be https://en.wikipedia.org/wiki/Lorem_ipsum .

• I do not quite see the specific point you want to illustrate with the quote. Or was it just included to cheer us up with some poetry. – quid Nov 11 '17 at 10:54
• @quid — I think that Will Jagy's more lucid Latin is intended to offer a balanced counterpoint to my meaningless word-salad greeking. – algoHolic Nov 11 '17 at 18:57
• Your blank space suggestion is a pretty good idea, Will Jagy. Thanks also for posting the Wikipedia citations. At first I was thinking you actually spoke Latin and just recited your text off the top of your head. I'm serious. – algoHolic Nov 11 '17 at 19:12
• @algoHolic I see. Given the use case I'd argue prose would have seem more appropriate. Maybe the start of In Catilinam could have been a nice compromise. – quid Nov 11 '17 at 19:31
• I am still very confused about the purpose of the stories about death by turtle (though Pratchett is always welcome in my world) – Stella Biderman Nov 11 '17 at 23:32
• @StellaBiderman The public need to be made aware of the grave danger posed by airborne tortoises. – Will Jagy Nov 12 '17 at 1:15
• Some seem to be distracted by the additional content. I thus trimmed it down. Sorry about that. I hope the subsequent lack of awareness about the dangers posed by airborne tortoises will not cause problems down the road. :-) – quid Nov 14 '17 at 8:08
• @quid, it's alright. When I put amusing stuff in, it usually stands for a day or two and then goes away. – Will Jagy Nov 14 '17 at 18:25