[Tex/LaTex] Error when trying to use the subcaption package

subcaptionsubfloats

When I try to use the subcaption package (\usepackage{subcaption}), I get some errors. However, using the subfigure package (\usepackage{subfigure}), the compilation is successful with no errors. I cannot figure out what is wrong…

here is a code example:

\documentclass[12pt, a4paper, oneside]{book}
\usepackage{fullpage}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{graphicx}
\usepackage{alltt}
\usepackage{latexsym}
\usepackage{exscale}
\usepackage[numbers, sort&compress]{natbib}
\usepackage{rotating}
\usepackage{changepage}
%\usepackage{notoccite}

%a useful package if you write url addresses:
%\usepackage{url}

\usepackage[labelfont=bf]{caption}
\usepackage{subcaption}

\usepackage{epsfig}

\begin{document}

\begin{figure}[htb]     
\centering
\subfigure[]
{
\label{fig: Image1} 
\includegraphics[width=76mm,height=60mm]{CordicStruc.pdf}
}
\subfigure[]
{
\label{fig: Image2} 
\includegraphics[width=76mm,height=60mm]{Diagram1.pdf}
}

\caption{\textbf{(a) Block diagram of floating-
point CORDIC co-processor architecture.} \textbf{(b) Pre-Process module in CORDIC co-processor.}}
\end{figure}

\end{document}

Best Answer

The problem is that they are different packages, and that they do not work in the same way. The subfigure package defines a \subfigure command that is used to create subfigures, as in

\subfigure{\includegraphics{image}}

subcaption does not define such a command, but it does define a subfigure environment, used as

\begin{subfigure}{.5\textwidth}
 \includegraphics{image}
 \caption{...}
\end{subfigure}

It also defines a \subcaptionbox command, that you can use.

Here is your code adapted to the subcaption package. I added examples for both the subfigure environment and \subcaptionbox command.

Note that the demo option to graphicx replaces the images with black rectangles, remove it for your own document.

\documentclass[12pt, a4paper, oneside]{book}
\usepackage[demo]{graphicx}

\usepackage[labelfont=bf]{caption}
\usepackage{subcaption}

\begin{document}

\begin{figure}[htb]     
\centering
\begin{subfigure}{\linewidth}
  \centering
  \includegraphics[width=76mm,height=60mm]{CordicStruc.pdf}
  \caption{}
  \label{fig: Image1} 
\end{subfigure}
\begin{subfigure}{\linewidth}
  \centering
  \includegraphics[width=76mm,height=60mm]{Diagram1.pdf}
  \caption{}
  \label{fig: Image1} 
\end{subfigure}
\caption{\textbf{(a) Block diagram of floating-
point CORDIC co-processor architecture.} \textbf{(b) Pre-Process module in CORDIC co-processor.}}
\end{figure}


\begin{figure}[htb]     
\centering
\subcaptionbox{}{\includegraphics[width=76mm,height=60mm]{CordicStruc.pdf}}
\subcaptionbox{}{\includegraphics[width=76mm,height=60mm]{Diagram1.pdf}}
\caption{\textbf{(a) Block diagram of floating-
point CORDIC co-processor architecture.} \textbf{(b) Pre-Process module in CORDIC co-processor.}}
\end{figure}

\end{document}
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