AD Two Argument Inverse Tangent Function

Syntax
theta = atan2(y, x)

Purpose
Determines an angle $\theta \in [ - \pi , + \pi ]$ such that $$\begin{array}{rcl} \sin ( \theta ) & = & y / \sqrt{ x^2 + y^2 } \\ \cos ( \theta ) & = & x / \sqrt{ x^2 + y^2 } \end{array}$$

y
The argument y has one of the following prototypes       const AD<Base>               &y      const VecAD<Base>::reference &y 
x
The argument x has one of the following prototypes       const AD<Base>               &x      const VecAD<Base>::reference &x 
theta
The result theta has prototype       AD<Base> theta 
Operation Sequence
The AD of Base operation sequence used to calculate theta is independent of x and y .

Example
The file atan2.cpp contains an example and test of this function. It returns true if it succeeds and false otherwise.