Java - Math atan(double) method

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Description

The Java Math atan(double a) returns the arc tangent of an angle, in the range of -pi/2 through pi/2. Special cases −

• If the argument is NaN, then the result is NaN.

• If the argument is zero, then the result is a zero with the same sign as the argument.

A result must be within 1 ulp of the correctly rounded result. Results must be semi-monotonic.

Declaration

Following is the declaration for java.lang.Math.atan() method

public static double atan(double a)

Parameters

a − the value whose arc tangent is to be returned.

Return Value

This method returns the arc tangent of the argument.

Exception

NA

Example 1

The following example shows the usage of Math atan() method.

package com.tutorialspoint;
public class MathDemo {
   public static void main(String[] args) {

      // get a variable x which is equal to PI/2
      double x = Math.PI / 2;

      // convert x to radians
      x = Math.toRadians(x);

      // get the arc tangent of x
      System.out.println("Math.atan(" + x + ")=" + Math.atan(x));
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Math.atan(0.027415567780803774)=0.0274087022410345

Example 2

The following example shows the usage of Math atan() method of 0° angle.

package com.tutorialspoint;
public class MathDemo {
   public static void main(String[] args) {

      // get a variable x which is equal to zero
      double x = 0.0d;

      // convert x to radians
      x = Math.toRadians(x);

      // get the arc tangent of x
      System.out.println("Math.atan(" + x + ")=" + Math.tan(x));
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Math.atan(0.0)=0.0

Example 3

The following example shows the usage of Math atan() method of 45° angle.

package com.tutorialspoint;
public class MathDemo {
   public static void main(String[] args) {

      // get a variable x which is equal to zero
      double x = 45.0d;

      // convert x to radians
      x = Math.toRadians(x);

      // get the arc tangent of x
      System.out.println("Math.atan(" + x + ")=" + Math.tan(x));
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Math.atan(0.7853981633974483)=0.9999999999999999