The standard inverse Trigonometric Arctangent function for x and y coordinates is supported, generating ATAN2 (x, y) and returning a value of type float. When dragging an Arctangent XY operator into a variable, the following tree element is created.
Variable Creation > Input > Variables: SQL Elements pane - Trigonometric > Arctangent XY
Columns and/or other expressions can be moved into the (empty) branch of the tree. There are no special properties for the Arctangent XY operator.