Diagonal brace with nested parenthesis

Question

I would to obtain a result similar to the image below. So far I only have \bigg( \Big( \big( a^q \big)^q \Big)^{\rotatebox{25}{$\cdots$}} \bigg)^q, without the brace.

I tried to follow this question, but there were no parenthesis and I was not able to circumvent this.

Hi, just a curiosity...for my opinion your question is good and I put +1. But do you have seen this image (I never I have seen this in a textbook)? :-) — Sebastiano, Feb 23 '21 at 13:01
@Sebastiano : thanks for your encouraging comment. I did the image myself, but admittedly I never saw this in a book – maybe in the future if we get nice answers to my question ;-) — Watson, Feb 23 '21 at 13:07
I don't even really know how to do it properly with a horizontal brace. — Watson, Feb 23 '21 at 13:09
Yes, I'm agree fully with you....In this moment for me it is very complicated done it in math-mode. I think with TiKZ or PSTricks it is very simple. I have understood your thought. :-) — Sebastiano, Feb 23 '21 at 13:09
@Sebastiano : a solution with TikZ (or PSTricks that I don't really know) would be fine. This is the approach used in the quesiton I linked. — Watson, Feb 23 '21 at 13:10
No no I have not seen truly your link. You wait a bit of time :-) . Here there are many excellents users. — Sebastiano, Feb 23 '21 at 13:13
See https://tex.stackexchange.com/questions/267171/nested-mathematical-functions — Steven B. Segletes, Feb 23 '21 at 13:32
@StevenB.Segletes : thanks, but I don't see how that question relates to mine about the digonal brace. — Watson, Feb 23 '21 at 13:36
@Watson I did not realize the diagonal brace was the essential part. I will see what I can do. — Steven B. Segletes, Feb 23 '21 at 13:41

campa · Accepted Answer · 2021-02-23T13:55:22.663

15

Very easy with horizontal brace; somewhat less easy with rotated brace. I have no time right now to implement a general solution, so I'll go with a brute-force version for now.

\documentclass{article}
\usepackage{mathtools}% loads amsmath and graphicx
\begin{document}
[
\biggl(\Bigl(\bigl(a
{% extra group for correct spacing
 \overbrace{
     {}^q \bigr)^q \Bigr)^{\rotatebox{20}{$\scriptstyle\dots$}} \biggr)^{!!q\mathstrut}
 }^{\text{$n$ times}}
}
]
[
\biggl(
\Bigl(
\bigl(a^q\bigr)^{q}
\Bigr)\quad
\biggr)^{
         !! q
         \setbox0=\hbox to 0pt{\hss
            \rotatebox{15}{$
              \overbrace{\kern1.8em\scriptstyle\mathstrut\dots\kern1.2em}^{\rotatebox{-15}{\scriptsize$n$ times}}
            $}%
         }%
         \lower1.5ex\box0
        }
]
\end{document}

edited Feb 23 '21 at 13:55

answered Feb 23 '21 at 13:36

campa

31,130

Thanks for your answer :-). In the horizontal case, it is possible to make the overbrace closer to the math formula? I tried to use \overbracket from mathtools but I am not able to get what I want. I tried to implement solutions from here, but negative depth does not seem to work anyway... – Watson Feb 23 '21 at 17:09
Probably using your idea with "\lower3ex\box0" can make it work, but I am not sure how. – Watson Feb 23 '21 at 17:13
@Watson No, you need no \lower in the first case. I've put an extra \mathstrut to increase the distance; you can simply remove that. – campa Feb 23 '21 at 19:38
Excellent works for every user! +1 for all. – Sebastiano Feb 23 '21 at 21:52

Steven B. Segletes · Answer 2 · 2021-02-23T14:02:26.177

11

As given in my answer at Nested Mathematical Functions

The .4pt stacking gap added with each nesting will determine the growth rate of the parens.

\documentclass{article} 
\usepackage{scalerel,stackengine,graphicx,amsmath}
\stackMath
\ignoremathstyle
\newcommand\Comp[1]{\scaleleftright{(}{\addstackgap[.4pt]{#1}}{)}}
\newcommand\rdots{\ThisStyle{.\raisebox{.1ex}{$\scriptstyle.$}%
  \raisebox{.2ex}{$\scriptstyle.$}}}
\begin{document} 
\[ 
\stackinset{r}{1pt}{t}{-14.5pt}{\rotatebox{6}
  {$\overbrace{\rule{30pt}{0pt}}^{\textrm{\tiny$n$ times}}$}}{%
\Comp{\Comp{\Comp{a^q}^q}^{\rdots}}^q}
\] 
\end{document}

Here's a version where the stackgap is increased to .6pt, to bring out the increasing size of parens:

edited Feb 23 '21 at 14:02

answered Feb 23 '21 at 13:39

Steven B. Segletes

237,551

1

Thanks but you are missing the diagonal brace above the parenthesis, so this does not really address my question. – Watson Feb 23 '21 at 13:40
1

@Watson Please see my revision. – Steven B. Segletes Feb 23 '21 at 14:02

Bernard · Answer 3 · 2021-02-23T19:14:21.303

A solution with pstricks-add:

\documentclass{article}
\usepackage{pstricks-add}
\begin{document}
[
\biggl(\Bigl(\bigl(a^{\pnode[0,1ex]{E}{q}}\bigr)^{! \rnode{F}{\scriptstyle q}}\Bigr)\enspace \biggr)^{!!\rnode{G}{\scriptstyle q}\pnode[0,1ex]{H}}%
\psset{singleline, braceWidth=1.2pt, braceWidthInner=2pt, braceWidthOuter=2pt, nodesepB=-2pt}
\psbracerot=14,ref=c, linewidth=0.3pt(E){\scriptstyle n:\mathrm{times}}%
\ncline[linestyle=dotted, dotsep=2.pt, nodesepA=4.5pt, nodesepB=3.2pt]{F}{G}
]
\end{document}

Diagonal brace with nested parenthesis

3 Answers3