I do not believe Latex has any simple means to do this, perhaps it can be done on this site. Is there any relatively simple way to rotate a numeral 90 degrees within an ordinary Latex formula? I may just draw the thing on a piece of paper, scan a jpeg, and post that...Or I can make it a separate image. Hmmm.

Lots of help from cardinal, here is the result, which I should try to quote or something, then you can try it at home



I was told this by a guy in Texas who claimed it was one of his students.
Old John says he has seen it in a book, so I guess that   happened first. 

The student was told
$$  \lim_{x \rightarrow 0} \; \; \frac{8}{x} \; \; = \; \; \infty.  $$
So, naturally, later he gave an answer  
$$  \lim_{x \rightarrow 0} \; \; \frac{5}{x} \; \; = \; \; \rotatebox[origin=c]{-90}{5}  $$
  • $\begingroup$ Do you want to do this in MathJax on this site or just in some other LaTeX document? If the latter, \rotatebox{angle}{stuff} should work. $\endgroup$ – cardinal Dec 17 '12 at 21:08
  • $\begingroup$ @cardinal let me try that.. $\endgroup$ – Will Jagy Dec 17 '12 at 21:16
  • $\begingroup$ No, I can't get that to work in either place. Note that I did it as a jpeg and it got an immediate downvote. There's no accounting for taste. $\endgroup$ – Will Jagy Dec 17 '12 at 21:21
  • $\begingroup$ In your LaTeX doc make sure you have \usepackage{graphicx} (there's no typo there!) in the preamble. I just tried this and it worked. :-) $\endgroup$ – cardinal Dec 17 '12 at 21:28
  • $\begingroup$ ...and just to clarify, angle is in degrees. ;-) $\endgroup$ – cardinal Dec 17 '12 at 21:33
  • $\begingroup$ @cardinal, it works at home. If I say 90 degrees it is counterclockwise, plus the numeral was centered vertically in comparison to the equals sign it follows. I preferred the 270 degree but for some reason the result is lowered vertically by about one character width. Let me try -90. $\endgroup$ – Will Jagy Dec 17 '12 at 22:02
  • $\begingroup$ Try [origin=c] before the first curly brace. $\endgroup$ – cardinal Dec 17 '12 at 22:03
  • $\begingroup$ @cardinal That's really good. If I knew how to do it on MSE I would repeat the answer, downvotes be damned. $\endgroup$ – Will Jagy Dec 17 '12 at 22:08
  • $\begingroup$ @WillJagy: I downvoted that answer because it seemed to me that it wasn't on topic for that question, although perhaps I was hasty. The conclusion of a sideways 5 is not a correct answer by incorrect reasoning. But now I see that I overlooked how the incorrect reasoning used by the student to justify the given answer for $8$ does match the topic. I'll remove my downvote if you undelete it. $\endgroup$ – Jonas Meyer Dec 17 '12 at 22:26
  • $\begingroup$ @JonasMeyer, thanks, I'm afraid my second try with a jpeg made the thing entirely blurry. It would be different if we knew how to do it with MSE typesetting. Note that cardinal's version really works. It would be nice to make the rotated 5 a bit larger, and that may be possible. I think it put the size for inline formulas instead of "displayed" formulas. I believe there is a way to override that. Meanwhile, after reading kjo's comment to StefanHansen I think we can accept that my answer is not what (s)he wants. $\endgroup$ – Will Jagy Dec 17 '12 at 22:42
  • $\begingroup$ Which answer are you talking about? $\endgroup$ – joriki Dec 18 '12 at 9:12
  • $\begingroup$ @joriki: Will gave an answer on the recently popular "right conclusion drawn from false steps" post. It is now deleted. $\endgroup$ – Willie Wong Dec 18 '12 at 13:12
  • $\begingroup$ @WillJagy: it seems that you are asking about how to do this in MathJax? The answer is that it is (so far) not possible. The graphicx package and the likes are just not part of the design goal of MathJax. You are better off doing it on your own computer. Compile the latex to dvi, and run dvipng on it to get the picture instead. $\endgroup$ – Willie Wong Dec 18 '12 at 13:14
  • $\begingroup$ @WillieWong, thanks. Let's see, dvipng . If it is like ps2pdf I will need to give a target filename. In any case, i already did it at home with cardinal's recipe, so it will not take long to see if i can use dvipng. I probably have it, I had to upgrade to current Ubuntu to get my scanner working. $\endgroup$ – Will Jagy Dec 19 '12 at 0:26
  • $\begingroup$ @WillieWong, I'm not getting it so far. I want it to just produce the final page out of 102 pages, that is how I compose stuff for MSE or MO, I put a newpage command into my long file MathOverthrow.tex and run Latex, next run dvips -p 102 MathOverthrow to produce a single page (102) as a postscipt, then ps2pdf MathOverthrow.ps MathOverthrow.pdf to get a pdf of just the one page. $\endgroup$ – Will Jagy Dec 19 '12 at 0:34

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