Q:

Stylesheet does not capitalize Polish letters correctly

I'm using SIAM's stylesheet (siamart.cls), and the stylesheet doesn't seem to correctly capitalize the Polish ł to an Ł.
\documentclass{siamart}
\usepackage[utf8]{inputenc}
\title{Title Łitłe}
\author{Authør Łauthør Thorłør}
\begin{document}
\maketitle
\end{document}

It correctly capitalizes the ø to an Ø.  I've also tried using '\l' and '\L'.
Question: Is the error on my side, or on the stylesheet's side?

A:

the issue is in the class file, which uses \uppercase for the case changing rather than \MakeUppercase. A fix:
\makeatletter
\def\@ucnt#1\thanks{\MakeUppercase{#1}\futurelet\@tempa\@ucnta}
\makeatother

The difference here is that \uppercase is a TeX primitive and can only case change 'native' input for the engine, whereas \MakeUppercase is set up to deal with a range of additional macro-based entries, including \l.

