Java Math.log1p() method

The java.lang.Math.log1p() is used to return the natural logarithm of the sum of the arguments and 1.

Syntax

Parameter

Return

If the argument is Positive value, this method will return the natural logarithm of a given value.
If the argument is NaN or less than -1, this method will return NaN.
If the argument is -1, this method will return Negative Infinity.
If the argument is Positive Infinity, this method will return Positive Infinity.
If the argument is positive or negative Zero, this method will return the Zero with the same sign as the argument.

Example 1

public class Log1pExample1
{
    public static void main(String[] args) 
    {
        double x = 26;
        // Input positive value, Output natural logarithm of x 	
        System.out.println(Math.log1p(x));
    }
}

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Output:

3.295836866004329

Example 2

public class Log1pExample2
{
    public static void main(String[] args) 
    {
        double x = -1.65;
        // Input less than -1, Output NaN
        System.out.println(Math.log1p(x));
    }
}

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Output:

NaN

Example 3

public class Log1pExample3
{
    public static void main(String[] args) 
    {
        double x = -1;
        // Input -1, Output -Infinity
        System.out.println(Math.log1p(x));
    }
}

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Output:

-Infinity

Example 4

public class Log1pExample4
{
    public static void main(String[] args) 
    {
        double x = 1.0/0;
        // Input positive infinity, Output positive infinity
        System.out.println(Math.log1p(x));
    }
}

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Output:

Infinity

Example 5

public class Log1pExample5
{
    public static void main(String[] args) 
    {
        double x = -0.0;
        // Input negative zero, Output negative zero
        System.out.println(Math.log1p(x));
    }
}

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Output: