# Enumerate with two columns

I'd like to have an enumerate with two columns. The first one report the name of the property and the second one can be a multiline text and it should be indented correctly. Thus second columns' text should follow the document's margin.

Something like this:

\begin{enumerate}
\item[] \textbf{Diagonal}, if all its elements outside the main diagonal are equal to zero, that is $\forall i\neq j$, $a_{ij} = 0$
\item[] \textbf{Scalar}, if all off-diagonal elements are zero and all on-diagonal elements are equal
\item[] \textbf{Identity}, if it's scalar and the elements on its main diagonal are all equal to 1, that is $\forall i$, $a_{ii} = 1$
\item[] \textbf{Lower triangular}, if all the entries above the main diagonal are zero, that is $\forall i > j$, $a_{ij} = 0$
\item[] \textbf{Upper triangular}, if all the entries below the main diagonal are zero, that is $\forall i < j$, $a_{ij} = 0$
\end{enumerate}
Below, a brief summary of the matrix operations used:
\begin{enumerate}
\item[] \textbf{Addition}: If $A$ and $B$ are matrices of the same size then the sum $A$ and $B$ is defined by $C = A + B$, where
$$c_{ij} = a_{ij}+b_{ij} \quad \forall i,j$$
\end{enumerate}


Using leandriis' link, this is what I obtained

"Diagonal" has \quad\quad after it, and I would like to indent all the text in the second column "Scalar" is the normal result.

• Will the list be longer than a single page? If not, you could use a table for this. – leandriis May 16 '19 at 11:47
• it'd be, actually. It's a list of properties. – JackLametta May 16 '19 at 11:50
• It sounds like you really want a description environment. If you use the enumitem package it is straightforward to set the widest "report name". – Andrew May 16 '19 at 11:56
• Could you please clarify the desired output? Do you want a number, than the name and then the long text or dou you want your list no be unnumbered? – leandriis May 16 '19 at 11:59
• When using a description environment, I don't think that @leandriis would recommend writing \item[] \textbf{Diagonal} (and likewise for the other list items). Instead, you should write \item[Diagonal], etc. – Mico May 16 '19 at 12:41

A longtable environment may be well suited for your typesetting needs.

You may see fit to adjust the width of the second column depending on (a) the width of the first column and (b) the overall width of the text block.

\documentclass{article}
\usepackage{array,longtable,ragged2e}
\newcolumntype{P}[1]{>{\RaggedRight\arraybackslash}p{#1}}

\begin{document}
\noindent
A matrix is said to be
\begin{longtable}{@{} >{\bfseries}l P{0.6\textwidth} @{}}
Diagonal & if all its elements outside the main diagonal are equal to zero, that is $\forall i\neq j$, $a_{ij} = 0$\\
Scalar & if all off-diagonal elements are zero and all on-diagonal elements are equal\\
Identity & if it is scalar and the elements on its main diagonal are all equal to 1, that is, $\forall i$, $a_{ii} = 1$ \\
Lower triangular & if all the entries above the main diagonal are zero, that is, $\forall i > j$, $a_{ij} = 0$ \\
Upper triangular & if all the entries below the main diagonal are zero, that is, $\forall i < j$, $a_{ij} = 0$
\end{longtable}

\bigskip\noindent
Below, a brief summary of the matrix operations used:
\begin{longtable}{@{} >{\bfseries}l P{0.7\textwidth} @{}}
Addition & If $A$ and $B$ are matrices of the same size then the sum of $A$ and $B$ is defined by $C = A + B$, where
$$c_{ij} = a_{ij}+b_{ij} \quad \forall i,j$$
\end{longtable}
\end{document}

• That's it! But the bold entries are not tabbed. Could you help me with it, please? – JackLametta May 16 '19 at 12:44
• and is it possible to have the same space between the elements that it's present in the document between the rows? – JackLametta May 16 '19 at 12:45
• @JackLametta - Please clarify what you mean by "the bold entries are not tabbed" and " the same space between the elements that it's present in the document between the rows". Thanks. – Mico May 16 '19 at 13:04
• I'd like to have the same interspace that there is between rows of the document also between the element of the longtable. – JackLametta May 16 '19 at 13:05
• @JackLametta - I'm afraid I don't follow you. If the row spacing in the longtable environment is different from that in the rest of your document, it must because you've made some changes to the default line spacing that you haven't told us about so far. – Mico May 16 '19 at 13:31