Rotation in \ddots

Question

I want to write a math equation that needs power of dots. I tried these code

{2^{2^{2^{\ddots^{2}}}}}

But the dots needs to be rotated

@user5376: you could perhaps use egreg's answer to a question about a rotated integral sign http://tex.stackexchange.com/questions/17416/create-a-new-integral-symbol/17419#17419 — , May 07 '11 at 11:01
@user5376: oh, sorry, I thought your dots were already with about the correct angle, as with \iddots from mathdots. Could prove easier indeed to rotate slightly \iddots than a lot \ddots, and perhaps actually \iddots already quasi solves your problem. — , May 07 '11 at 11:28

score 17 · Answer 1 · answered May 07 '11 at 17:52

17

Adapted from The TeXbook, Exercise 18.45:

\def\rddots#1{\cdot^{\cdot^{\cdot^{#1}}}}
$ 2^{2^{\rddots2}} $
\bye

enter image description here

answered May 07 '11 at 17:52

morbusg

25,490
4
81
162

(+1) Again, I feel like it provides a better alignment than \iddots! – chl May 07 '11 at 18:46
1

When used like this, on math.stackexchange.com each subsequent dot is smaller... – Tomáš Zato Jan 26 '14 at 00:40
@Tomáš: That's because MSE uses [mathjax], which is a bit different thing from TeX and I am not very familiar with it. There is a glyph with [unicode-math], \adots for U+022F0, but I don't think it's available with mathjax (nor if it's the appropriate glyph for this). If mathjax understands different math styles, you could try the more explicit definition: \def\rddots#1{{\scriptstyle\cdot}^{{\scriptstyle\cdot}^{{\scriptstyle\cdot}^{#1}}}} – morbusg Jan 26 '14 at 09:06
@TomášZato: Or, with Unicode, something like: \def\sadots{{\scriptstyle\char"22F0\relax}} (note that there is no family or class definitions, so for use just in this context). – morbusg Jan 26 '14 at 09:12

chl · Answer 2 · 2011-05-07T07:43:34.957

10

An easy way would be to replace \ddots by \udots from the MnSymbol package, or \iddots from mathdots (better rendering in math mode).

enter image description here

edited May 07 '11 at 07:43

answered May 07 '11 at 07:38

chl

8,890

I could not define the MnSymbol package, when I define it the program does not compile the file – user5376 May 07 '11 at 08:09
@user5376 Add \usepackage{MnSymbol} in your preamble. Still, I'd recommend using \iddots instead. – chl May 07 '11 at 08:11
In TexLive you find the package mathdots in the package texlive-generic-extra – loved.by.Jesus May 18 '20 at 12:31

score 7 · Answer 3 · 2011-05-07T12:29:44.573

7

you could try (with 5 dots for the fun of it!):

\[
  {2^{2^{2^{\mathstrut^{.^{.^{.^{.^{.^{\raisebox{-.5\height}{$\scriptscriptstyle
                        2$}}}}}}}}}}}
\]

\[
  {2^{2^{2^{\mathstrut^{.^{.^{.^{.^{.^{\raisebox{-.25\height}{$\scriptscriptstyle
                        2$}}}}}}}}}}}
\]

or the simpler

\[
  {2^{2^{2^{\mathstrut^{.^{.^{.^{\raisebox{-.25\height}{$\scriptscriptstyle
                        2$}}}}}}}}}
\]

\[ 
  {2^{2^{2^{\mathstrut^{.^{.^{.^{2}}}}}}}}
\]

they give (respectively):

iterated powers of two

edited May 07 '11 at 12:29

answered May 07 '11 at 11:52

@jbfu (+1) Your 2nd solution seems to provide a better alignment. – chl May 07 '11 at 12:30
@chl yes, I agree. The \mathstrut is to put the first dot higher than where it would fall otherwise. One could fine-tune that positioning if needed. – May 07 '11 at 12:55

Rotation in \ddots

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