This function returns y = atan(u), with -∞ < u < ∞, where y is an angle.
function atan extends Modelica.Math.Icons.AxisCenter; input Real u annotation( Dialog(__Dymola_label = "<html><i>u</i></html>")); output Q.Angle y annotation( Dialog(__Dymola_label = "<html><i>y</i></html>")); end atan;