Lambda 未在 MDPI Journal 中呈现

Question

为什么下面的公式 (2) 中的 lambda 没有呈现？我犯了什么错误？您需要 MDPI 日志模板中的 Definitions 文件夹来运行它。

\documentclass[energies,article,submit,pdftex,moreauthors]{Definitions/mdpi} 
\usepackage[utf8]{inputenc}

\title{test_lambda}

\begin{document}

\maketitle

\section{Introduction}

Like this, it works:

\begin{equation}
    \lambda
\end{equation}

But here, it does not work:

\begin{equation}
        \mathbf{w_{out} = r^{\mathit{T}}M(M^{\mathit{T}}M + \mathit{\lambda}^{\mathrm{2}}I)^{-1}},
\end{equation}

And like this $\lambda$, it also works.

\end{document}

输出：

编辑：获取MDPI模板的链接：

模板

Answer 1

该字体不包含粗体数学版本的 lambda。如果您可以接受普通数学 lambda，则可以使用\mathnormal切换回正常粗细：

\documentclass[energies,article,submit,pdftex,moreauthors]{Definitions/mdpi} 
\usepackage[utf8]{inputenc}
\firstpage{1} 
\makeatletter 
\setcounter{page}{\@firstpage} 
\makeatother
\pubvolume{1}
\issuenum{1}
\articlenumber{0}
\pubyear{2023}
\copyrightyear{2023}
%\externaleditor{Academic Editor: Firstname Lastname}
\datereceived{ } 
\daterevised{ } % Comment out if no revised date
\dateaccepted{ } 
\datepublished{ } 
%\datecorrected{} % For corrected papers: "Corrected: XXX" date in the original paper.
%\dateretracted{} % For corrected papers: "Retracted: XXX" date in the original paper.
\hreflink{https://doi.org/} % If needed use \linebreak
\Title{Title}

% MDPI internal command: Title for citation in the left column
\TitleCitation{Title}

% Author Orchid ID: enter ID or remove command
\newcommand{\orcidauthorA}{0000-0000-0000-000X} % Add \orcidA{} behind the author's name
%\newcommand{\orcidauthorB}{0000-0000-0000-000X} % Add \orcidB{} behind the author's name

% Authors, for the paper (add full first names)
\Author{Firstname Lastname $^{1,\dagger,\ddagger}$\orcidA{}, Firstname Lastname $^{2,\ddagger}$ and Firstname Lastname $^{2,}$*}

%\longauthorlist{yes}

% MDPI internal command: Authors, for metadata in PDF
\AuthorNames{Firstname Lastname, Firstname Lastname and Firstname Lastname}

% MDPI internal command: Authors, for citation in the left column
\AuthorCitation{Lastname, F.; Lastname, F.; Lastname, F.}
% If this is a Chicago style journal: Lastname, Firstname, Firstname Lastname, and Firstname Lastname.

% Affiliations / Addresses (Add [1] after \address if there is only one affiliation.)
\address{%
$^{1}$ \quad Affiliation 1; [email protected]\\
$^{2}$ \quad Affiliation 2; [email protected]}

% Contact information of the corresponding author
\corres{Correspondence: [email protected]; Tel.: (optional; include country code; if there are multiple corresponding authors, add author initials) +xx-xxxx-xxx-xxxx (F.L.)}

% Current address and/or shared authorship
\firstnote{Current address: Affiliation 3.} 
\secondnote{These authors contributed equally to this work.}

\begin{document}

\maketitle

\section{Introduction}

Like this, it works:

\begin{equation}
    \lambda
\end{equation}

But here, it does not work:

\begin{equation}
        \mathbf{w_{out} = r^{\mathit{T}}M(M^{\mathit{T}}M + \mathnormal{\lambda}^{\mathrm{2}}I)^{-1}},
\end{equation}

And like this $\lambda$, it also works.

\end{document}