# No fancy parentheses {} in align-environment [duplicate]

In the following code lines, the fancy parantheses F{x} do not appear:

\documentclass[11pt, a4paper]{article}
\usepackage{amsmath}
\usepackage{amsfonts}

\begin{document}

\begin{align}\label{Hilbert}
\operatorname{F}{\hat{x}(t)} = \hat{X}(j\omega) &= \operatorname{Im}\left\{X(j\omega)\right\} \operatorname{sgn(\omega)} -j\operatorname{Re}\left\{X(j\omega)\right\} \operatorname{sgn(\omega)}\\
\end{align}

\end{document}


I assume it is because I am using the align-environment. But I need it.

• I suppose you mean braces. Just write \operatorname{F}\{\hat{x}(t)\}. – Bernard Mar 9 '17 at 10:07
• this is unrelated to align. The braces are not printed for the same reason the braces in \hat{X} are not printed, {..} are tex syntax characters (by default) so do not print as themselves. – David Carlisle Mar 9 '17 at 10:14
• – Torbjørn T. Mar 19 '17 at 13:50

I think you should set up macros for \F, \Re, and \Im (after first undefining the the existing macros for \Re and \Im). All three macros should be defined to take one argument, which will automatically be encased in curly braces. Providing the macros will greatly simply the code needed for the equation.

\documentclass[11pt, a4paper]{article}
\usepackage{amsmath} % for "\DeclareMathOperator" macro

\let\Im\relax \let\Re\relax  % first, un-define \Im and \Re
\newcommand\F[1] {\operatorname{F} \{#1\}}
\newcommand\Im[1]{\operatorname{Im}\{#1\}}
\newcommand\Re[1]{\operatorname{Re}\{#1\}}
\DeclareMathOperator{\sgn}{sgn}

\begin{document}
$$\label{Hilbert} \F{\hat{x}(t)} = \widehat{X}(j\omega) = \Im{X(j\omega)} \sgn(\omega) -j\Re{X(j\omega)} \sgn(\omega)$$
\end{document}

• thx Mico, this is really helpful! - Can you tell me what the [1] after every newdommand does? – user123551 Mar 20 '17 at 10:31
• @Luk - The [1] particle size can indicates that the macro takes 1 argument. – Mico Mar 20 '17 at 10:54