My references say that \intertext must immediately follow \\ but this example suggests that the effect is the same without \\. Or am I missing something?

\documentclass[12pt]{article}
\usepackage{amsmath}
\begin{document}
\begin{align}
x&=y \\
\intertext{together with}
y&=z
\intertext{implies that}
x&=z.
\end{align}

\end{document}

Le 25/05/2023 à 07:37, jfh a écrit :
> My references say that \intertext must immediately follow \\

In my references too.

> but this example suggests that the effect is the same without \\. Or am I missing something?
>
> [snap good example]

The code of \intertext begins with
\ifvmode\else\\\@empty\fi
Inside a math environment we aren't in vertical mode, then \ifvmode is
false, then \intertext put a '\\'.
Conclusion: the references are strange... and my references are very
serious (for instance LaTeX Companion). Perhaps just a taste of logic:
we should write an intertext after a line is complete?!?

Jean-Côme Charpentier

On Saturday, May 27, 2023 at 11:11:34 PM UTC+12, Jean-Côme Charpentier wrote:
> Le 25/05/2023 à 07:37, jfh a écrit :
> > My references say that \intertext must immediately follow \\
> In my references too.
> > but this example suggests that the effect is the same without \\. Or am I missing something?
> >
> > [snap good example]
>
> The code of \intertext begins with
> \ifvmode\else\\\@empty\fi
> Inside a math environment we aren't in vertical mode, then \ifvmode is
> false, then \intertext put a '\\'.
> Conclusion: the references are strange... and my references are very
> serious (for instance LaTeX Companion). Perhaps just a taste of logic:
> we should write an intertext after a line is complete?!?
>
> Jean-Côme Charpentier
Thank you Jean-Côme . My references were Kopka & Daly 3rd ed. and several web pages.

On Sunday, May 28, 2023 at 3:09:23 PM UTC+12, jfh wrote:
> On Saturday, May 27, 2023 at 11:11:34 PM UTC+12, Jean-Côme Charpentier wrote:
> > Le 25/05/2023 à 07:37, jfh a écrit :
> > > My references say that \intertext must immediately follow \\
> > In my references too.
> > > but this example suggests that the effect is the same without \\. Or am I missing something?
> > >
> > > [snap good example]
> >
> > The code of \intertext begins with
> > \ifvmode\else\\\@empty\fi
> > Inside a math environment we aren't in vertical mode, then \ifvmode is
> > false, then \intertext put a '\\'.
> > Conclusion: the references are strange... and my references are very
> > serious (for instance LaTeX Companion). Perhaps just a taste of logic:
> > we should write an intertext after a line is complete?!?
> >
> > Jean-Côme Charpentier
> Thank you Jean-Côme .erences were Kopka & Daly 3rd ed. and several web pages.
Intertext without \\ also works even if it's the first thing after \begin{align} . So does shortintertext, as here:

\documentclass{article}
\usepackage{mathtools}
\begin{document}
Trying shortintertext (in italics) and intertext without \verb+\\+
\begin{align}
\shortintertext{\emph{If}}
x &= y
\shortintertext{\emph{and}}
y &= z
\shortintertext{\emph{then}}
x &= z.
\intertext{If}
p &< q
\intertext{and}
q &< r
\intertext{then}
p &< r.
\end{align}
\end{document}