#     
## Overview
**`DoubleUnaryOperator`** is a functional interface that represents an operation on a single double-valued argument and produces a double-valued result. The **`applyAsDouble()` method** is the functional method of the interface.

The `DoubleUnaryOperator` interface is defined in the `java.util.function` package. To import the `DoubleUnaryOperator` interface check the following import statement.
```
import java.util.function.DoubleUnaryOperator;
```


## Syntax

---

``` java
double applyAsDouble(double operand);
```

---
## Parameters 

- **`double operand`**: The `double` valued operand.

## Return value

This method returns a `double` valued result.

import java.util.function.DoubleUnaryOperator;

public class Main {

    public static void main(String[] args){
        DoubleUnaryOperator squareOfNumFunction = num -> num * num;
        double arg = 5.43;
        System.out.println("Result of applyAsDouble() on squareOfNumFunction --> " + squareOfNumFunction.applyAsDouble(arg));
    }
}

## Explanation

- **Line 1**: We import the `DoubleUnaryOperator` interface from the `function` package.
- **Line 6**: We define an implementation of the `DoubleUnaryOperator` interface called `squareOfNumFunction`. `squareOfNumFunction` accepts a double-valued argument and returns the result square of the given argument.
- **Line 7**: We define a `double` value called `arg`.
- **Line 8**: We print the result of using the `applyAsDouble()` method and pass `arg` as an argument.

What is the DoubleUnaryOperator functional interface in Java?

DoubleUnaryOperator represents a single double-valued argument operation producing a double result using applyAsDouble().

What is the DoubleUnaryOperator functional interface in Java?

Overview

Syntax

Parameters

Return value

Code

Explanation