[Tex/LaTex] Trigonometric function script?

Question

This question already has answers here:

Define additional math operators to be typeset in roman

(7 answers)

Closed 7 years ago.

Is there a script for the sinc function analogous to \sin for sinus?
If not, what method should I use to insert it in a equation?

Answer 1

Use \DeclareMathOperator{operatorcommandname}{operator name} in the preamble for function or operator names that should be printed upright.

\documentclass{article}
\usepackage{amsmath}

\DeclareMathOperator{\sinc}{sinc}
\DeclareMathOperator{\si}{si}


\begin{document}

\begin{align}
 \si(x) &= \dfrac{\sin(x)}{x}  \\
 \sinc(x) &= \si(\pi x) 
\end{align}


\begin{align}
  \int\limits_{-\infty}^{\infty}\si(x)\,\mathrm{d}x &= \pi \\ 
  \int\limits_{-\infty}^{\infty}\sinc(x)\,\mathrm{d}x &= 1 
\end{align}
\end{document}