First character of `align*` not in math mode?

Question

I'm having a really strange problem with the align* environment from amsmath (it happens with align, aligned, gather, etc. as well). For some reason, the first character is not in math mode, but the rest are. The following code:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align}
  \ifmmode t \else f \fi
  \ifmmode t \else f \fi & =
  \ifmmode t \else f \fi
\end{align}
\end{document}

Produces:

This is obviously a simplified version of what I'm actually trying to do, but I'm wondering what causes this behavior?

Welcome to TeX.SE! From showed image follows, that all characters are in "math" mode. — Zarko, Jan 20 '22 at 04:22
That conditional at the start might be the issue. Try with \leavevmode\ifmmode .... — Werner, Jan 20 '22 at 04:33
@Zarko Yeah, the characters themselves are, but the \ifmmode clearly says that its not, hence why I was confused. — Kevin Fisher, Jan 20 '22 at 04:41
@Werner That works! Thanks. What does \leavevmode do? Also do you want to make that an answer so I can mark it correct? — Kevin Fisher, Jan 20 '22 at 04:42
@KevinFisher See tex core - What does \leavevmode do? - TeX - LaTeX Stack Exchange and the linked questions from that one — although to digest that answer you might want to read on horizontal and vertical mode (TeXbook page ??? or TeX by topic page 72.) — user202729, Jan 20 '22 at 05:10
Probably same issue as math mode - Correct usage of \ifmmode - TeX - LaTeX Stack Exchange or math mode - \ifmmode doesn't seem to work correctly inside an array environment - TeX - LaTeX Stack Exchange . — user202729, Jan 20 '22 at 05:12
@user202729 You're totally right, I'm not sure how I missed those. Should this be marked as duplicate? — Kevin Fisher, Jan 20 '22 at 05:25
Okay, looks good. (the answer in the first one looks better, although funnily the (question, answer) pair have the exact same number of votes. — user202729, Jan 20 '22 at 05:28
Does this answer your question? \ifmmode doesn't seem to work correctly inside an array environment — user202729, Jan 20 '22 at 05:28

First character of `align*` not in math mode?

0 Answers0