StrictMath expm1() Method in Java With Examples

The java.lang.StrictMath.expm1() is an inbuilt method in Java which is used to return the exponential e^num -1 for a given value of num. The method gives rise to four different cases: 

• The method returns NaN when the given argument is NaN.
• The result is positive infinity when the argument is positive infinity.
• The result is negative infinity when the argument is negative infinity.
• For 0 the methods return 0 with the same sign as the argument.

Syntax : 

public static double expm1(double num)

Parameters: This method accepts one parameter num of double type and refers to the value on which the exponential operation is to be performed.
Return Value: The method will return the result of e^num – 1 operation.
Examples :

Input: num = (1.0/0.0)
Output: Infinity

Input: 32.2
Output: 9.644557735961714E13

Below programs illustrate the java.lang.StrictMath.expm1() method: 
Program 1: 

java

// Java program to illustrate the
// java.lang.StrictMath.expm1()
import java.lang.*;

public class Geeks {

public static void main(String[] args) {

    double num1 = 0.0, num2 = -(1.0/0.0);
        double num3 = (1.0/0.0), num4 = 32.2;

    /*It  returns e^num - 1 */
    double eValue = StrictMath.expm1(num1);
    System.out.println("The expm1 Value of "+
                              num1+" = "+eValue);

    eValue = StrictMath.expm1(num2);
    System.out.println("The expm1 Value of "+
                              num2+" = "+eValue);

    eValue = StrictMath.expm1(num3);
    System.out.println("The expm1 Value of "+
                              num3+" = "+eValue);

    eValue = StrictMath.expm1(num4);
    System.out.println("The expm1 Value of "+
                              num4+" = "+eValue);}
}

Program 2: 

java

// Java program to illustrate the
// java.lang.StrictMath.expm1()
import java.lang.*;

public class Geeks {

public static void main(String[] args) {

    double num1 = 2.0 , num2 = -51.8;
        double num3 = 61.0, num4 = -32.2;

    /*It  returns e^num - 1 */
    double eValue = StrictMath.expm1(num1);
    System.out.println("The expm1 Value of "+
                              num1+" = "+eValue);

    eValue = StrictMath.expm1(num2);
    System.out.println("The expm1 Value of "+
                              num2+" = "+eValue);

    eValue = StrictMath.expm1(num3);
    System.out.println("The expm1 Value of "+
                              num3+" = "+eValue);

    eValue = StrictMath.expm1(num4);
    System.out.println("The expm1 Value of "+
                              num4+" = "+eValue);
}
}