[Tex/LaTex] Parentheses between \big and \Big

amsmathdelimitersparentheses

Is there a way to create parentheses in math mode that have an extension between that of the commands \big (too small) and \Big (too big)? The amsmath package documentation defines the delimiters in this way:

\renewcommand{\big}{\bBigg@\@ne}
\renewcommand{\Big}{\bBigg@{1.5}}
\renewcommand{\bigg}{\bBigg@\tw@}
\renewcommand{\Bigg}{\bBigg@{2.5}}

but if I try with something like

\makeatletter
\renewcommand{\Pbig}{\bBigg@{1.25}}
\makeatother

in the preamble and then I write $\Pbig($ in the code, it doesn't work; it only produces the same results as \big or \Big.

Best Answer

Here I use scalerel package to create a delimiter that is 1.5pt larger above and below (3 pt total) than \big . I call it \pig. I limit the overall width to 5pt

While it will technically "work" with any delimiter, it is really intended for either ( or \{. Use with [ produces an undesirable line thickness. EDITED to minimize this issue and provide two alternatives.

In this manifestation (the intermediate size is a scaled up \big), the bracket line thickness is slightly too thick:

\documentclass{article}
\usepackage{scalerel,stackengine}
\newcommand\pig[1]{\scalerel*[5pt]{\big#1}{%
  \ensurestackMath{\addstackgap[1.5pt]{\big#1}}}}
\newcommand\pigl[1]{\mathopen{\pig{#1}}}
\newcommand\pigr[1]{\mathclose{\pig{#1}}}
\begin{document}
$ \bigl( \pigl( \Bigl($

$ \bigl\{ \pigl\{ \Bigl\{$

$ \bigl[ \pigl[  \Bigl[$ $<$---BAD!
\end{document}

enter image description here

In this second manifestation, one \big is changed to \Big in the \pig definition (so that the intermediate size is a scaled down \Big), and the maximum width was increased to 5.5pt. Now, the bracket line thickness is just slightly too thin:

\documentclass{article}
\usepackage{scalerel,stackengine}
\newcommand\pig[1]{\scalerel*[5.5pt]{\Big#1}{%
  \ensurestackMath{\addstackgap[1.5pt]{\big#1}}}}
\newcommand\pigl[1]{\mathopen{\pig{#1}}}
\newcommand\pigr[1]{\mathclose{\pig{#1}}}
\begin{document}
$ \bigl( \pigl( \Bigl($

$ \bigl\{ \pigl\{ \Bigl\{$

$ \bigl[ \pigl[  \Bigl[$ $<$---BAD!
\end{document}

enter image description here

Perhaps one of the versions is [almost] suitable.

Related Question