absolute value

in mathematics, the absolute value of a real number $x$ is the non-negative value of $x$ without regard to its sign, shown as “abs(x)”, or more commonly shown as $|x|$

the absolute value function is piecewise-defined: $|x|=\{\begin{array}{ll}-x& \text{if }x<0\\ +x& \text{if }x\ge 0\end{array}$