Size of calligraphic number

Question

I asked in this question Calligraphic numbers how to write a calligraphic number and got an answer.

Now I need a notation for k-subsets and use the answer as follows:

\documentclass[a4paper,11pt]{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}    
\usepackage{xspace}

%%% for caligraphic number
\newcommand*{\textcal}[1]{%
  % family qzc: Font TeX Gyre Chorus (package tgchorus)
  % family pzc: Font Zapf Chancery (package chancery)
  \textit{\fontfamily{qzc}\selectfont#1}%
}

\newcommand{\ksubsets}[1]{\ensuremath{\textcal{2}^{#1}_{=k}}\xspace}

\begin{document}

\begin{equation}
\sum_{P'\in\ksubsets{P}} \prod_{x \in P'} p_{x}
\end{equation}

\end{document}

But I do not like how this looks. The 2 is too small. How can I change that?

Answer 1

The cleanest solution is to define a new font family; adjust the [1.2] scaling factor to suit; scaling up of 20% seems to be good.

\documentclass[a4paper,11pt]{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}    


% Calligraphic numbers
\DeclareFontFamily{OT1}{sqzc}{}
\DeclareFontShape{OT1}{sqzc}{m}{it}{<-> s * [1.2] rm-qzcmi}{}
\DeclareFontShape{OT1}{sqzc}{m}{sl}{<->ssub * qzc/m/it}{}
\DeclareFontShape{OT1}{sqzc}{m}{n}{<->ssub * qzc/m/it}{}

\DeclareFontFamily{T1}{sqzc}{}
\DeclareFontShape{T1}{sqzc}{m}{it}{<-> [1.2] ec-qzcmi}{}
\DeclareFontShape{T1}{sqzc}{m}{sl}{<->sub * qzc/m/it}{}
\DeclareFontShape{T1}{sqzc}{m}{n}{<->sub * qzc/m/it}{}

\DeclareMathAlphabet{\zcal}{\encodingdefault}{sqzc}{m}{it}

% My command
\newcommand{\ksubsets}[1]{\mathop{\zcal{2}}\nolimits^{#1}_{=k}}

\begin{document}

\begin{equation}
\zcal{123}+123 \ne \sum_{P'\in\ksubsets{P}} \prod_{x \in P'} p_{x}
\end{equation}

\end{document}

This "wastes" a math alphabet, but should pose no problem if you don't load many math fonts. It has an advantage: in the definition of the \ksubsets command one can use \mathop, that slightly lowers the 2, making for a better alignment.

Answer 2

You could use \mathlarger of the relsize package, to enlarge just the 2:

\newcommand{\ksubsets}[1]{\ensuremath{\mathlarger{\textcal{2}}^{#1}_{=k}}\xspace}