Adding crossbars to letters

Question

I've been trying to make these symbols to use in math mode:

I tried modifying the explanations from

• d with a little line through the top of it
• Vertical spacing using kern in a custom symbol

but I don't really have any idea what I'm doing. The closest I've got is

f\mkern-6.5mu\mathchar'204\mkern-2mu

I'm using the following packages

• \usepackage[utf8]{inputenc}
• \usepackage[T1]{fontenc}
• \usepackage{libertine}
• \usepackage{libertinust1math}

Answer 1

You can do this with fontspec and Unicode combining accents, adjusting the positioning of the combining bar with \kern.

\tracinglostchars=2
\documentclass{article}
\usepackage{unicode-math}
\usepackage{libertinus} % Loads unicode-math and Libertinus Math.
\pagestyle{empty}
\newcommand\pstroke{\mathord{\mathit{p\kern -0.1em ^^^^0332}}}
\newcommand\tstroke{\mathord{\mathit{t^^^^0335}}}
\newcommand\fstroke{\mathord{\mathit{f^^^^0335}}}
\begin{document}
[ \pstroke \neq \tstroke \neq \fstroke ]
\end{document}

Answer 2

Using the bar that's found in position "84 of libertinust1-mathrm. Fine tune the parameters if you want more precise positioning.

The first parameter is the vertical shift, the second parameter is the horizontal shift, the third parameter is the horizontal scaling. The bar is always vertically scaled at 80%.

\documentclass{article}
\usepackage{amsmath,graphicx}
\usepackage{libertinus}
\usepackage{libertinust1math}
\makeatletter
\DeclareRobustCommand{\tbar}{\text{\addbar@{-0.35ex}{0.07em}{1}}t}
\DeclareRobustCommand{\fbar}{\text{\addbar@{-0.35ex}{0.07em}{1.1}}f}
\DeclareRobustCommand{\pbar}{\text{\addbar@{-1.25ex}{-0.01em}{1}}p}
\newcommand{\addbar@}[3]{%
  \makebox[0pt][l]{%
    \raisebox{#1}[0pt][0pt]{%
      \kern#2
      \scalebox{#3}[0.8]{$\m@th\mathchar"84$}%
    }%
  }%
}
\makeatother
\begin{document}
$\tbar\ \fbar\ \pbar$
$\scriptstyle\tbar\ \fbar\ \pbar$
$\scriptscriptstyle\tbar\ \fbar\ \pbar$
\end{document}