C# | Math.Atan() Method

Math.Atan() is an inbuilt Math class method which returns the angle whose tangent is given as a double value argument. If the argument is NaN, then the result will be NaN.

Syntax:

public static double Atan(double num)

Parameter:

num: It is the number that represents a tangent and type of this parameter is System.Double.

Return Type: Returns an angle Θ, measured in radians and its type is System.Double. Here the angle is always measured in radians, such that -π/2 ≤ Θ ≤ π/2.

Examples:

Input  : Math.Atan(1)
Output : 0.785398163397448
     
Input  : Math.Atan(0.0)
Output : 0

Input  : Math.Atan(-0.0)
Output : 0

Input  : Math.Atan(Double.PositiveInfinity)
Output : 1.5707963267949

Input  : Math.Atan(Double.NegativeInfinity)
Output : -1.5707963267949

Program: To illustrate the Math.Atan() method

// C# program to demonstrate working
// of Math.Atan() method
using System;

class Geeks {

    // Main Method
    public static void Main(String []args)
    {
        double a = Math.PI;

        // using Math.Atan() method
        Console.WriteLine(Math.Atan(a));

        double d = 0.0;
        double e = -0.0;
        double posi = Double.PositiveInfinity;
        double nega = Double.NegativeInfinity;
        double nan = Double.NaN;

        Console.WriteLine(Math.Atan(1));

        // Input positive zero
        // Output positive zero
        Console.WriteLine(Math.Atan(d));

        // Input negative zero
        // Output positive zero
        Console.WriteLine(Math.Atan(e));

        // input PositiveInfinity
        // Output 1.5707963267949
        Console.WriteLine(Math.Atan(posi));

        // input NegativeInfinity
        // Output -1.5707963267949
        Console.WriteLine(Math.Atan(nega));

        // input NaN
        // Output NaN
        Console.WriteLine(Math.Atan(nan));
    }
}

Output:

1.26262725567891
0.785398163397448
0
0
1.5707963267949
-1.5707963267949
NaN

Reference: https://msdn.microsoft.com/en-us/library/system.math.atan