# How the LOG2() function works in Mariadb?

The `LOG2()`

function is a mathematical function that returns the logarithm of a number to the base 2.

The `LOG2()`

function is a mathematical function that returns the logarithm of a number to the base 2. The logarithm to the base 2 is also known as the binary logarithm, as it represents the number of times a number can be divided by 2. The `LOG2()`

function is useful for performing various calculations, such as binary search, bit manipulation, entropy, etc.

## Syntax

The syntax of the `LOG2()`

function is as follows:

```
LOG2(number)
```

The `number`

argument is the number whose logarithm to the base 2 is to be returned. The `number`

argument must be a positive value, otherwise the function returns `NULL`

.

The `LOG2()`

function returns a decimal value that represents the logarithm of the `number`

to the base 2. If the `number`

argument is `NULL`

, the function returns `NULL`

.

## Examples

### Example 1: Basic usage of the LOG2() function

The following example shows how to use the `LOG2()`

function with a simple number. It returns the logarithm of the number 8 to the base 2.

```
SELECT LOG2(8);
```

The output is:

`3`

This means that the logarithm of 8 to the base 2 is 3, which means that 8 can be divided by 2 three times.

### Example 2: Using the LOG2() function with a decimal number

The following example shows how to use the `LOG2()`

function with a decimal number. It returns the logarithm of the number 2.5 to the base 2.

```
SELECT LOG2(2.5);
```

The output is:

`1.321928094887362`

This means that the logarithm of 2.5 to the base 2 is approximately 1.321928094887362.

### Example 3: Using the LOG2() function with a negative number

The following example shows what happens when the `LOG2()`

function is used with a negative number. It returns `NULL`

, indicating that the logarithm to the base 2 is not defined for negative numbers.

```
SELECT LOG2(-5);
```

The output is:

`NULL`

This means that the logarithm of -5 to the base 2 is not defined.

## Related Functions

There are some other functions that are related to the `LOG2()`

function in Mariadb. They are:

`LOG()`

: This function returns the natural logarithm of a number. The natural logarithm is the logarithm to the base`e`

, where`e`

is the mathematical constant that is approximately equal to 2.71828. The`LOG()`

function can also accept an optional second argument that specifies a different base for the logarithm.`LOG10()`

: This function returns the logarithm of a number to the base 10. The logarithm to the base 10 is also known as the common logarithm, as it is widely used in mathematics and science.`POW()`

: This function returns the value of a number raised to the power of another number. It is the inverse of the`LOG()`

function, meaning that`POW(2, LOG2(x)) = x`

for any positive`x`

.`BIT_COUNT()`

: This function returns the number of bits that are set to 1 in a binary representation of a number. It is related to the`LOG2()`

function, as it can be used to calculate the minimum number of bits required to represent a number.

Here are some examples of using these related functions:

```
-- Get the natural logarithm of 10
SELECT LOG(10);
-- Get the logarithm of 100 to the base 10
SELECT LOG10(100);
-- Get the value of 2 raised to the power of 3
SELECT POW(2, 3);
-- Get the number of bits that are set to 1 in the binary representation of 13
SELECT BIT_COUNT(13);
```

## Conclusion

In this article, we have learned how the `LOG2()`

function works in Mariadb. We have seen its syntax, examples, and related functions. We have also learned how to use the `LOG2()`

function to calculate the logarithm of a number to the base 2. The `LOG2()`

function is a useful function to perform various calculations, such as binary search, bit manipulation, entropy, etc.