Java log1p Function

The Java log1p Function is one of the Java Math Library function which is used to return the natural logarithm of the sum of the arguments and 1. For the small values, the result of log1p(a) is much closer to the true result of ln(1 + a) than the floating-point evaluation of log(1.0 + a).

In this article, we will show you, How to write Math.log1p function in Java Programming language with example.

Java log1p Function syntax

The basic syntax of the Math.log1p in Java Programming language is as shown below. Following function will accept positive double value as argument and returns the logarithmic value of the specified expression or Value.

static double log1p(double number); //Return Type is Double

// In order to use in program: 
Math.log1p(double number);

Number: It can be a double value or a valid numerical expression for which you want to find the natural logarithm.

If the number argument is positive double value, Math.log1p function will return the natural logarithm of a given value.
If the number argument is negative double value, Math.log1p function will return NaN.
When the number argument is not a number, java Math.log1p function will return NaN.
If the number argument is positive infinity, Math.log1p function will return the result as Positive Infinity
If the number argument is negative infinity, Math.log1p function will return the result as Negative Infinity
When the number argument is positive or negative zero, Java Math.log1p function will return the result as Zero

Java log1p Function Example

The Java Math.log1p Function allows you to find the natural logarithm of a specified expression or an individual double value. In this Java program, We are going to find the same and display the output.

JAVA CODE

// Java Math.log1p Function
package MathFunctions;

public class Log1pMethod {
	public static void main(String[] args) {
		double a = Math.log1p(100.90 + 150.10 - 220.50 + 10.50);
		System.out.println("Log1p Result = " + a);	

		System.out.println("\nLog1p Result of Zero: " + Math.log1p(0));
		
		System.out.println("\nLog1p Result of Positive Number: " + Math.log1p(1));
		System.out.println("Log1p Result of Positive Number: " + Math.log1p(10.95));
		
		System.out.println("\nLog1p Result of Negative Number: " + Math.log1p(-2.70));
		System.out.println("Log1p Result of Negative Number: " + Math.log1p(-6.50));		
	}
}

OUTPUT

ANALYSIS

First, We declared variable of type Double and performed the Math.log1p function directly on expression.

double a = Math.log1p(100.90 + 150.10 - 220.50 + 10.50);
System.out.println("Log1p Result = " + a);

Next, We used the Java log1p Function directly on Positive double values.

System.out.println("\nLog1p Result of Positive Number: " + Math.log1p(1));
System.out.println("Log1p Result of Positive Number: " + Math.log1p(10.95));

Next, We used the java Math.log1p Function directly on Negative double values. As you can see from the screenshot, it is returning NaN for negative values.

System.out.println("\nLog1p Result of Negative Number: " + Math.log1p(-2.70));
System.out.println("Log1p Result of Negative Number: " + Math.log1p(-6.50));

Java log1p on Array example

In this Java program we will show you, How to find the natural logarithm of bulk data. Here, we are going to declare an Array of double type and find the natural logarithm of each and every element in an array.

JAVA CODE

package MathFunctions;

public class Log1pMethodOnArrays {
	public static void main(String[] args) {
		
		double [] logArray = {21.35, 44.98, -58.41, -9.5987, -0, 92.38, 14.4897};

		for (int i = 0; i < logArray.length; i++) {
			System.out.format("Log1p Result of Array Element = %.4f\n", Math.log1p(logArray[i]));
		}
	}
}

OUTPUT

ANALYSIS

First, We declared an Array of double type and assigned some random values.

double [] logArray = {21.35, 44.98, -58.41, -9.5987, -0, 92.38, 14.4897};

Next, We used the Java For Loop to iterate the Array. Within the For Loop, we initialized the i value as 0. Next, compiler will check for the condition (i < logArray.length). As along the condition is True, statement inside the for loop will be executed.

TIP: logArray.length is used to find the length of an array.

for (int i = 0; i < logArray.length; i++) {

Following statements will print the output. If you observe the code snippet, we used the Math.log1p Function directly inside the System.out.format statement. Here, compiler will call the Java Math.log1p method ( static double log1p(double number) ) to find the natural logarithm of corresponding values.

System.out.format("Log1p Result of Array Element = %.4f\n", Math.log1p(logArray[i]));

NOTE: If you want to find the natural logarithm of a single item then use: Math.log1p(myArray[index_position])

Java log1p function on Arraylist example

In this Java program we are going to declare an arraylist of double type and find the natural logarithm of list elements.

JAVA CODE

package MathFunctions;

import java.util.ArrayList;

public class Log1pMethodOnArrayList {
	public static void main(String[] args) {
		
		ArrayList<Double> logpList = new ArrayList<Double>(5);
		logpList.add(245.998);
		logpList.add(-480.05);
		logpList.add(250.9876);
		logpList.add(140.01);
		logpList.add(2015.98);
		logpList.add(-897.1898);
		
		for (double x : logpList) {
			System.out.println("Log1p Result of ArrayList =  " + Math.log1p(x));
		}
	}
}

OUTPUT

ANALYSIS

Within the Java log1p function, first, We declared an ArrayList of double type and assigned some random values.

ArrayList<Double> logpList = new ArrayList<Double>(5);
logpList.add(245.998);
logpList.add(-480.05);
logpList.add(250.9876);
logpList.add(140.01);
logpList.add(2015.98);
logpList.add(-897.1898);

Next, We used the For Loop to iterate the double values in ArrayList

for (double x : logpList) {

Following statements will print the output. Here, compiler will call the java Math.log1p method ( static double log1p(double x) ) to find the natural logarithm of corresponding values.

System.out.println("Log1p Result of ArrayList =  " + Math.log1p(x));

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