[Math] What does horizontal line above variable means

complex numbersnotation

I have a simple equation which looks like that except that there placed vector signs there are straight horizontal lines:
\begin{equation}
\ z = i^8 + \overline{z_1} \cdot \overline{z_1} -z_1 ;\\
\ z_1 = 2-3i , \\
\ z_2 = 1+i
\end{equation}

What does these horizontal lines means?

Best Answer

Complex conjugate. ${}{}{}{}{}$

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