# Java StrictMath log1p() method with example

StrictMath Class log1p() method: Here, we are going to learn about the log1p() method of StrictMath Class with its syntax and example.
Submitted by Preeti Jain, on December 26, 2019

## StrictMath Class log1p() method

• log1p() method is available in java.lang package.
• log1p() method is used to return (the logarithm of the sum of the given argument and 1 like log(1+d) in the method.
• log1p() method is a static method so it is accessible with the class name and if we try to access the method with the class object then also we will not get an error.
• We need to remember one thing if we pass smaller values for the given argument so the final calculated result of log1p(d) is nearer to the exact result of ln(1+d) than the double floating-point calculation of log(1.0+d).
• log1p() method does not throw any exception.

Syntax:

```    public static double log1p(double d);
```

Parameter(s):

• double d – represents the double type argument.

Return value:

The return type of this method is double – it returns the logarithm (1+d) of the given argument.

Note:

• If we pass NaN, method returns NaN.
• If we a value which is less than -1, method returns NaN.
• If we pass a positive infinity, method returns the same (i.e. positive infinity).
• If we pass a negative infinity, method returns NaN.
• If we pass 0 (negative or positive), method returns the same with the same sign.

Example:

```// Java program to demonstrate the example
// of log1p(double d) method of StrictMath class.

public class Log1p {
public static void main(String[] args) {
// variable declarations
double d1 = 7.0 / 0.0;
double d2 = -7.0 / 0.0;
double d3 = 0.0;
double d4 = -0.0;
double d5 = 6054.2;

// Display previous value of d1,d2,d3,d4 and d5
System.out.println("d1: " + d1);
System.out.println("d2: " + d2);
System.out.println("d3: " + d3);
System.out.println("d4: " + d4);
System.out.println("d5: " + d5);

// Here , we will get (Infinity) because we are
// passing parameter whose value is (Infinity)
System.out.println("StrictMath.log1p(d1): " + StrictMath.log1p(d1));

// Here , we will get (NaN) because we are
// passing parameter whose value is (-Infinity)
System.out.println("StrictMath.log1p(d2): " + StrictMath.log1p(d2));

// Here , we will get (0.0) because we are
// passing parameter whose value is (0.0)
System.out.println("StrictMath.log1p(d3): " + StrictMath.log1p(d3));

// Here , we will get (-0.0) because we are
// passing parameter whose value is (-0.0)
System.out.println("StrictMath.log1p(d4): " + StrictMath.log1p(d4));

// Here , we will get (log [1 + d5]) and we are
// passing parameter whose value is (6054.2)
System.out.println("StrictMath.log1p(d5): " + StrictMath.log1p(d5));
}
}
```

Output

```d1: Infinity
d2: -Infinity
d3: 0.0
d4: -0.0
d5: 6054.2
StrictMath.log1p(d1): Infinity
StrictMath.log1p(d2): NaN
StrictMath.log1p(d3): 0.0
StrictMath.log1p(d4): -0.0
StrictMath.log1p(d5): 8.708672685994957
```

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