What is Math.Atan2() in C#?

C# has a built-in Math class that provides useful mathematical functions and operations. The class has the Atan2() function, which is used to compute the angle whose tangent is the quotient of two specified numbers.

Syntax

public static double Atan2 (double yaxis, double xaxis);

Parameters

  • xaxis: This parameter is of the Double type and represents the x coordinate of the input point.
  • yaxis: This parameter is of the Double type and represents the y coordinate of the input point.

Return value

  • Double: This value returns an angle Θ measured in radians, and its type is Double. Its range is:

    • -π <= θ <= π (radians)

    where tan(θ) = yaxis / xaxis

    • For (xaxis, yaxis) in quadrant 1, 0 < θ < π/2.

    • For (xaxis, yaxis) in quadrant 2, π/2 < θ ≤ π.

    • For (xaxis, yaxis) in quadrant 3, -π < θ < -π/2.

    • For (xaxis, yaxis) in quadrant 4, -π/2 < θ < 0.

    Boundary points

    • If yaxis = 0 and xaxis > 0, θ = 0.

    • If yaxis = 0 and xaxis < 0, θ = π.

    • If yaxis > 0 and xaxis = 0, θ = π/2.

    • If yaxis < 0 and xaxis = 0, θ = -π/2.

    • If yaxis = 0 and xaxis = 0, θ = 0.

  • NaN: The function returns this if xaxis or yaxis is NaN, PositiveInfinity, or NegativeInfinity.

Example

using System;
class Educative
{
    static void Main()
    {
        double result = Math.Atan2(20,15);
        System.Console.WriteLine("Atan2(20,15) = "+ result + " radians");
        double result1 = Math.Atan2(-20,-15);
        System.Console.WriteLine("Atan2(-20,-15) = "+ result1 + " radians");
        
        double result2 = Math.Atan2(-20,Double.NaN);
        System.Console.WriteLine("Atan2(-20,NaN) = "+ result2);
    }
}

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