[Tex/LaTex] this font called?

fonts

What is the font in this figure and how to produce it using latex?

The font is surrounded by red circles.

Unknown Font

Best Answer

The font is Computer Modern Sans. The document is not particularly well typeset, as it mixes Computer Modern math with Times New Roman for text, which should never be done.

I can reproduce the output with the following input, apart from the line length:

\documentclass[a4paper]{article}
\usepackage{times}

\addtolength{\textwidth}{-2.78cm}

\begin{document}

A $k\times n$ matrix $G$ is said to \emph{fit} another $k\times n$ matrix $M$
if $\mathsf{supp}(G_i)\subseteq\mathsf{supp}(M_i)$ for all $i\in[k]$. Moreover
if $M$ is a binary matrix and $\mathsf{supp}(G_i)=\mathsf{supp}(M_i)$ for all
$i\in[k]$ then $M$ is called the \emph{support matrix} of $G$, denoted
$\mathsf{supp}(G)$.

\end{document}

enter image description here

So the font is the one obtained with \mathsf and, since \usepackage{times} doesn't change the math fonts, it's Computer Modern Sans.

You get better results if you do \usepackage{mathptmx}:

\documentclass[a4paper]{article}
\usepackage{mathptmx}
\usepackage{amsmath}

\DeclareMathOperator{\supp}{\mathsf{supp}}

\addtolength{\textwidth}{-3cm}

\begin{document}

A $k\times n$ matrix $G$ is said to \emph{fit} another $k\times n$ matrix $M$
if $\supp(G_i)\subseteq\supp(M_i)$ for all $i\in[k]$. Moreover
if $M$ is a binary matrix and $\mathsf{supp}(G_i)=\supp(M_i)$ for all
$i\in[k]$ then $M$ is called the \emph{support matrix} of $G$, denoted
$\supp(G)$.

\end{document}

enter image description here

Better yet, if you do

\usepackage{newtxtext,newtxmath}

instead of \usepackage{mathptmx}:

enter image description here

However, in this case Helvetica is used.

Requested comment

Computer Modern (Roman and Math) and Times New Roman are visually incompatible with each other: the main reasons are the thickness of strokes and the form of the serifs. In math, the incompatibility is even stronger, because the letters take very different shapes. Compare the “k” and “n” in the first picture with the same letters in the second one, but also look at the first picture from a certain distance: the letters in math formulas are clearly much thinner than in text, which spoils the greyness of the page.

On the other hand, Computer Modern Sans and Times are not “absolutely” incompatible: the mix between a serif and a sans serif typefaces is a question of personal taste, mainly.

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