Getting italic Computer Modern numerals with Times Roman font elsewhere in math

Question

I am typesetting a document in Times Roman (using txfonts). However, the digits (0123456789) when italicized (with \textit{} or \emph{}) do not have the same script-y look as they do in Computer modern. With Times, they merely look slanted.

Is there a way I can use the italic versions of digits from Computer Modern in my otherwise Times Roman document? [I would like to have them available as separate symbols, say \eins, \zwei etc., instead of overwriting the default numbers.] I use script digits for a few purposes, including section headings, characteristic functions of sets (\mathord{\textit{1}}_A), power classes of sets (\mathord{\textit{2}}^\varOmega).

Answer 1

A comment up front: The txfonts package, which provides both text and math fonts, has been superseded for several years now by a pair of packages: newtxtext and newtxmath. I can see no good reason for using the txfonts package if the vintage of your TeX distribution is more recent than, say, 2012.

If you can at all switch to LuaLaTeX, it becomes very straightforward to handle almost any number of math fonts side-by-side within a single document. Indeed, for what you appear to have in mind, something like the following setup is entirely sufficient:

\usepackage[no-math]{fontspec}
\setmainfont{STIX Two Text}[Numbers={OldStyle,Proportional}]
\usepackage{unicode-math}
\setmathfont{STIX Two Math}

The "STIX Two" text and math fonts may be downloaded free of charge from https://sourceforge.net/projects/stixfonts/

A full MWE (the use of "old-style", proportional-width text-mode numerals is optional):

% !TeX program = lualatex
\documentclass{article}
\usepackage[no-math]{fontspec}
\setmainfont{STIX Two Text}[Numbers={OldStyle,Proportional}]
\usepackage{unicode-math}
\setmathfont{STIX Two Math}

% macros for characteristic functions and power classes of sets
\newcommand\cfset[1]{\mathit{1}_{\mkern-1.5mu#1}}
\newcommand\pcset[1]{\mathit{2}^{#1}}

\begin{document}
0123456789abcdef   % text: oldstyle numerals, proportional width

$0123456789abcdef$ % math: lining style numerals, fixed width

$\mathit{0123456789abcdef}$ "\mathit" automatically uses Latin Modern glyphs

$\cfset{K}$ $\pcset{\varpi}$
\end{document}