argmin doesn't work in algorithmic table

Question

I'm using \DeclareMathOperator*{\argmin}{argmin} for getting the argmin parameter. Every thing is Ok expect if I type it inside algorithmic table, it fails to show the correct output. In the below picture, the scenario is shown

The code for this picture is

\documentclass{article}
\usepackage{algorithm,algpseudocode,float}
\usepackage{amsmath}

\DeclareMathOperator*{\argmin}{argmin}


%-----------
\makeatletter
\newenvironment{breakablealgorithm}
  {% \begin{breakablealgorithm}
   \begin{center}
     \refstepcounter{algorithm}% New algorithm
     \hrule height.8pt depth0pt \kern2pt% \@fs@pre for \@fs@ruled
     \renewcommand{\caption}[2][\relax]{% Make a new \caption
       {\raggedright\textbf{\ALG@name~\thealgorithm} ##2\par}%
       \ifx\relax##1\relax % #1 is \relax
         \addcontentsline{loa}{algorithm}{\protect\numberline{\thealgorithm}##2}%
       \else % #1 is not \relax
         \addcontentsline{loa}{algorithm}{\protect\numberline{\thealgorithm}##1}%
       \fi
       \kern2pt\hrule\kern2pt
     }
  }{% \end{breakablealgorithm}
     \kern2pt\hrule\relax% \@fs@post for \@fs@ruled
   \end{center}
  }
\makeatother

\begin{document}


$$
a = \argmin_s
$$

\begin{breakablealgorithm}
  \caption{XXXXXXXXX}
  \begin{algorithmic}[1]
    \State{$\text{A} = \argmin_s B$}
\end{algorithmic}
\end{breakablealgorithm}



\end{document}

My question is now why it doesn't work properly inside the algorithm.

Answer 1

Inside the algorithmic environment you're in regular text-style when entering math mode. And operators in text-style have their limits displayed in that way rather than underneath/over top. You have to force an explicit \displaystyle to have it set in the same way:

\documentclass{article}
\usepackage{algorithm,algpseudocode,amsmath}

\DeclareMathOperator*{\argmin}{argmin}

\begin{document}

\[
  a = \argmin_s
\]

\begin{algorithm}
  \caption{XXXXXXXXX}
  \begin{algorithmic}[1]
    \State $\text{A} = \displaystyle\argmin_s B$
  \end{algorithmic}
\end{algorithm}

\end{document}

I wouldn't do it though.