# Style Pseudocode in LaTeX

I'm trying to replicate the style of the following pseudocode taken from 'The Elements of Statistical Learning'.

I've tried with algorithm,algorithmic and enumerate (for the item) but I haven't reached the result below...

This is just a nested enumerate inside an algorithm environment: \documentclass{report}

\usepackage{algorithm,amsmath,lipsum,xcolor,caption}
\DeclareMathOperator{\sgn}{sign}
\DeclareCaptionFont{lightblue}{\color{blue}}
\captionsetup[algorithm]{labelfont={bf,lightblue}, textfont={it}}
\renewcommand{\thealgorithm}{\thechapter.\arabic{algorithm}}

\begin{document}

\setcounter{chapter}{10}% Just for this example
\lipsum

\begin{algorithm}[htb]
\begin{enumerate}
\item
Initialize the observation weights $w_i = 1/N$, $i = 1, 2, \dots, N$

\item
For $m = 1$ to $M$:
\begin{enumerate}
\item
Fit a classifier $G_m(x)$ to the training data using weights $w_i$.

\item
Compute
$\text{err}_m = \frac{\sum_{i=1}^N w_i I(y_i \neq G_m(x_i))}{\sum_{i=1}^N w_i}.$

\item
Compute $\alpha_m = \log((1 - \text{err}_m) / \text{err}_m)$.

\item
Set $w_i \leftarrow w_i \cdot \exp [\alpha_m \cdot I(y_i \neq G_m(x_i))]$, $i = 1, 2, \dots, N$.
\end{enumerate}

\item
Output $G(x) = \sgn \bigl[ \sum_{m = 1}^M \alpha_m G_m(x) \bigr]$.
\end{enumerate}
\end{algorithm}

\lipsum

\end{document}

• this looks really neat to me – Jinhua Wang Aug 31 '19 at 19:50