Double - Atan2

Returns the angle whose tangent is the quotient of two specified numbers.

Try it

public static void Main()
{
    double x = 1.0;
    double y = 2.0;
    double angle;
    double radians;

    // Calculate the tangent of 30 degrees.
    angle = 30;
    radians = angle * (Math.PI / 180);

	// C# Extension Method: Double - Atan2
    radians = y.Atan2(x);
    angle = radians * (180 / Math.PI);

    Console.WriteLine("The arctangent of the angle formed by the x-axis and ");
    Console.WriteLine("a vector to point ({0},{1}) is {2}, ", x, y, radians);
    Console.WriteLine("which is equivalent to {0} degrees.", angle);

}

View Source
using System;

public static partial class Extensions
{
    /// <summary>
    ///     Returns the angle whose tangent is the quotient of two specified numbers.
    /// </summary>
    /// <param name="y">The y coordinate of a point.</param>
    /// <param name="x">The x coordinate of a point.</param>
    /// <returns>
    ///     An angle, ?, measured in radians, such that -?????, and tan(?) =  / , where (, ) is a point in the Cartesian
    ///     plane. Observe the following: For (, ) in quadrant 1, 0 &lt; ? &lt; ?/2.For (, ) in quadrant 2, ?/2 &lt;
    ///     ???.For (, ) in quadrant 3, -? &lt; ? &lt; -?/2.For (, ) in quadrant 4, -?/2 &lt; ? &lt; 0.For points on the
    ///     boundaries of the quadrants, the return value is the following:If y is 0 and x is not negative, ? = 0.If y is
    ///     0 and x is negative, ? = ?.If y is positive and x is 0, ? = ?/2.If y is negative and x is 0, ? = -?/2.If  or
    ///     is , or if  and  are either  or , the method returns .
    /// </returns>
    public static Double Atan2(this Double y, Double x)
    {
        return Math.Atan2(y, x);
    }
}