[Tex/LaTex] Sub-numbering in an algorithm

algorithmicxalgorithmsline-numbering

How can I add sub steps to a numbered step in an algorithm as shown in the image:

\documentclass{article}

\usepackage{algorithm,algpseudocode}

\begin{document}

\begin{algorithm}
  \caption{Square Root Cubature Kalman Filter SRCKF}

  \textbf{Time update}

  \begin{algorithmic}[1]
    \State Factorize the state error covariance matrix 
      \begin{equation}
        P_{k-1|k-1} = S_{k-1|k-1}S_{k-1|k-1}^T
      \end{equation}  
    \State Evaluate the cubature points (i=1,2,...,$m = 2n_x$)
      \begin{equation}
        X_{i,k-1|k-1} = \hat{x}_{k-1|k-1} + S_{i,k-1|k-1}\zeta_i
      \end{equation}
    \State Evaluate the propagated cubature points through the process equation (i=1,2,...,$m = 2n_x$)
      \begin{equation}
      X_{i,k|k-1}^*=f(X_{i,k-1|k-1},u_{k-1})
      \end{equation} 
    \State Estimate the predicted state


    \State Estimate the predicted error covariance
      \begin{equation}
      P_{k|k-1}=\frac{1}{m}\sum_{i=1}^m{X_{i,k|k-1}^*X_{i,k|k-1}^{*T}}-\hat{x}_{k|k-1}\hat{x}_{k|k-1}^T+Q_{k-1} 
      \end{equation} 
  \end{algorithmic}
\end{algorithm}

\end{document}

Best Answer

You can use a list-like environment algsubstates like I defined below. The enumeration formatting matches that of the regular \State (using \footnotesize):

\documentclass{article}

\usepackage{algorithm,algpseudocode}

\newcounter{algsubstate}
\renewcommand{\thealgsubstate}{\alph{algsubstate}}
\newenvironment{algsubstates}
  {\setcounter{algsubstate}{0}%
   \renewcommand{\State}{%
     \stepcounter{algsubstate}%
     \Statex {\footnotesize\thealgsubstate:}\space}}
  {}

\begin{document}

\begin{algorithm}
  \caption{Square Root Cubature Kalman Filter SRCKF}

  \textbf{Time update}

  \begin{algorithmic}[1]
    \State Factorize the state error covariance matrix 
      \begin{equation}
        P_{k-1 \mid k-1} = S_{k-1 \mid k-1} S_{k-1 \mid k-1}^T
      \end{equation}  
    \State Evaluate the cubature points ($i = 1,2,\ldots,m = 2n_x$)
      \begin{equation}
        X_{i,k-1 \mid k-1} = \hat{x}_{k-1 \mid k-1} + S_{i,k-1 \mid k-1} \zeta_i
      \end{equation}
    \State Evaluate the propagated cubature points through the process equation ($i = 1,2,\ldots,m = 2n_x$)
      \begin{equation}
        X_{i,k \mid k-1}^* = f(X_{i,k-1 \mid k-1},u_{k-1})
      \end{equation} 
    \State Estimate the predicted state
      \begin{algsubstates}
        \State First
        \State Second
        \State Third
        \State Last
      \end{algsubstates}
    \State Estimate the predicted error covariance
      \begin{equation}
      P_{k \mid k-1} = \frac{1}{m}\sum_{i=1}^m X_{i,k \mid k-1}^* X_{i,k \mid k-1}^{*T}
        - \hat{x}_{k \mid k-1}\hat{x}_{k \mid k-1}^T + Q_{k-1} 
      \end{equation} 
  \end{algorithmic}
\end{algorithm}

\end{document}

The above code doesn't allow for referencing within the algsubstates. However, the following should:

\newcounter{algsubstate}
\makeatletter
\renewcommand{\thealgsubstate}{\arabic{ALG@line}.\alph{algsubstate}}
\makeatother
\newenvironment{algsubstates}
  {\setcounter{algsubstate}{0}%
   \renewcommand{\State}{%
     \refstepcounter{algsubstate}%
     \Statex {\footnotesize\alph{algsubstate}:}\space}}
  {}

\references will be of the form <state>.<substate> (but could be changed).

Related Solutions

[Tex/LaTex] algorithm numbering

You need to use \caption before \label; otherwise, the string picked for the reference will be the last one where an anchor was set (typically the one of a sectional unit), in this case, the one from \chapter. Here's a modified version of your code showing the desired result:

\documentclass[11pt, letterpaper]{book}

\renewcommand{\thechapter}{\Roman{chapter}}
\renewcommand{\thesection}{\arabic{section}}

\usepackage[chapter]{algorithm}
\usepackage{algorithmicx}
\usepackage{algpseudocode}

\renewcommand{\thealgorithm}{\arabic{chapter}.\arabic{algorithm}} 

\begin{document} 

\chapter{First Chapter}

\begin{algorithm} 
  \begin{algorithmic}[1]
    \State Some code here 
  \end{algorithmic} 
  \caption{A test algorithm}
  \label{alg:algorithm1}
\end{algorithm}

Algorithm~\ref{alg:algorithm1} states blah blah blah and algorithm~\ref{alg:algorithm2} states blah blah blah. 

\begin{algorithm} 
  \begin{algorithmic}[1]
    \State Some code here 
  \end{algorithmic} 
  \caption{Another test algorithm}
  \label{alg:algorithm2}
\end{algorithm}

\end{document}

enter image description here

If you don't want to give explicit captions to your algorithms, you can use the \phantomcaption command from the caption package (this, however, could be confusing since you are referencing by number some objects which aren't really numbered):

\documentclass[11pt, letterpaper]{book}
\usepackage{caption}

\renewcommand{\thechapter}{\Roman{chapter}}
\renewcommand{\thesection}{\arabic{section}}

\usepackage[chapter]{algorithm}
\usepackage{algorithmicx}
\usepackage{algpseudocode}

\renewcommand{\thealgorithm}{\arabic{chapter}.\arabic{algorithm}} 

\begin{document} 

\chapter{First Chapter}

\begin{algorithm} 
  \begin{algorithmic}[1]
    \State Some code here 
  \end{algorithmic} 
  \phantomcaption
  \label{alg:algorithm1}
\end{algorithm}

Algorithm~\ref{alg:algorithm1} states blah blah blah and algorithm~\ref{alg:algorithm2} states blah blah blah. 

\begin{algorithm} 
  \begin{algorithmic}[1]
    \State Some code here 
  \end{algorithmic} 
  \phantomcaption
  \label{alg:algorithm2}
\end{algorithm}

\end{document}

enter image description here

[Tex/LaTex] Algorithm in LaTeX

It is not completely clear to me which algorithm typesetting package are you using, since you did not include the document preamble, and your code is a strange jumble of several different syntaxes, mostly looking like the old algorithms package syntax, but not quite. Your tags seem to indicate that you are using the algorithmicx bundle, so I assume that you use the algpseudocode package. You need to correct some syntax, for example algpseudocode does noy capitalize command, only first letter, so you should have \If ... \Else ... \EndIf etc.

Also, command \For and \If take an argument, so you need

\If{something something}

The \If does not use \Then, you should leave that out.

Every line must have a command, so you should either define your own commands for things like "Given:", or just use \State.

The following will hopefully do what you expect it to do:

\documentclass{article}
\usepackage{algpseudocode}
\usepackage{algorithm}
\begin{document}
\begin{algorithm}
   \caption{Blah blah}
   \begin{algorithmic}[1]
      \State Given: User-Noun Matrix $X$
      \For{$i = 1 \to n$}
         \State Let $S_i$ = {$s{i,j}$ | $0\le j \le l_i$} be set of nodes which have links to $i$;
         \If{$\left(l_i=0 \hbox{OR} l_i=1 \right)$}
            \State $b_i=0$;
         \Else
            \State Compute the similarity score vectors $r_{s,1},r_{s,2},...,r_{s,l_i}$ for each $S_i=s_1,s_2,...s_{l_i}$; \\
            \State Construct $l_i \times l_i$ matrix $R_i= \left[r_{s,1},r_{s,2},...,r_{s,l_i}\right]$;
            \State Take the average of all non-diagonal elements in $R_i$ to obtain $\hat{r_s}$;
            \State $b_i= 1/\hat{r_s}$;
         \EndIf
      \EndFor
    \State \Return vector $b$ of bridging scores;
\end{algorithmic}
\end{algorithm}
\end{document}

The algorithmicx bundle have pretty good documentation with a number of examples, I suggest you take a look at it.

Best Answer

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