This function returns y = atan2(u1,u2) such that tan(y) = u1/u2 and y is in the range -pi < y ≤ pi. u2 may be zero, provided u1 is not zero. Usually u1, u2 is provided in such a form that u1 = sin(y) and u2 = cos(y):
function atan2 extends Modelica.Math.Icons.AxisCenter; input Real u1 "First independent variable"; input Real u2 "Second independent variable"; output Modelica.Units.SI.Angle y "Dependent variable y=atan2(u1, u2)=atan(u1/u2)"; end atan2;