@twocolumnfalse seemingly has no effect

Question

I am writing a document of the type \documentclass[twocolumn]{article}, I want to use a pgfornament right after the title centered. If I use it like that:

\begin{@twocolumnfalse}
\begin{center}
test
\end{center}
\end{@twocolumnfalse}

Where test is the ornament (or, it doesn't really matter, same problem when I am using the text test). My problem is that the \begin{@twocolumnfalse} doesn't do anything at all. The text or the ornament are still centered in the left column, although they should be in the center of the whole page. What am I doing wrong?

Answer 1

LaTeX has a boolean flag \if@twocolumn which is set true if the twocolumn option has been used. Some code (typically \maketitle) checks this boolean and uses different layout in one or two column modes.

Your code fragment is equivalent to

{\@twocolumnfalse
\begin{center}
test
\end{center}
}

So it just sets the flag to false but doesn't actually change the layout. center does not check the boolean at all so acts as normal. In standard latex \begin{document}, floating environments like figure, \maketitle/titlepage and abstract are the only places that check this boolean.

---

in two column mode article class uses

          \twocolumn[\@maketitle]%

to set the title, the optional argument here is placed in a spanning box that is full page width before the two column starts.

I would guess that your real use case should add the ornament to the definition of \@maketitle so that it comes within this spanning box.