# How the LN() function works in Mariadb?

The `LN()`

function is a mathematical function that returns the natural logarithm of a given number.

The `LN()`

function is a mathematical function that returns the natural logarithm of a given number. The natural logarithm is the logarithm to the base `e`

, where `e`

is the mathematical constant approximately equal to `2.71828`

. The `LN()`

function is a synonym for the `LOG()`

function and can be used interchangeably.

## Syntax

The syntax of the `LN()`

function is as follows:

```
LN(x)
```

The `x`

is the number whose natural logarithm is to be calculated. It can be any valid numeric expression in Mariadb, such as column values, literal values, or variables. The `x`

must be a positive number, otherwise the function returns `NULL`

.

The `LN()`

function returns a numeric value that represents the natural logarithm of the input number. If the input number is `NULL`

, the function returns `NULL`

.

## Examples

In this section, we will show some examples of how to use the `LN()`

function in Mariadb.

### Example 1: Calculating the natural logarithm of a literal value

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

function to calculate the natural logarithm of a literal value.

```
SELECT LN(1);
```

The output is:

```
LN(1)
-----
0
```

As you can see, the `LN()`

function returns `0`

, which is the natural logarithm of `1`

.

### Example 2: Calculating the natural logarithm of a column value

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

function to calculate the natural logarithm of a column value. Suppose we have a table called `numbers`

that stores some numeric values, such as `x`

and `y`

. The table has the following data:

id | x | y |
---|---|---|

1 | 2 | 3 |

2 | 4 | 5 |

3 | 6 | 7 |

4 | 8 | 9 |

We can use the `LN()`

function to calculate the natural logarithm of the `x`

column, as shown below:

```
SELECT id, x, LN(x) AS ln_x FROM numbers;
```

The output is:

id | x | ln_x |
---|---|---|

1 | 2 | 0.6931471805599453 |

2 | 4 | 1.3862943611198906 |

3 | 6 | 1.791759469228055 |

4 | 8 | 2.0794415416798357 |

As you can see, the `LN()`

function returns the natural logarithm of the `x`

column values.

### Example 3: Calculating the natural logarithm of a variable value

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

function to calculate the natural logarithm of a variable value. Suppose we have a variable that stores a numeric value, such as `@z`

. We can use the `LN()`

function to calculate the natural logarithm of the variable value, as shown below:

```
SET @z = 10;
SELECT LN(@z);
```

The output is:

```
LN(@z)
------
2.302585092994046
```

As you can see, the `LN()`

function returns the natural logarithm of the variable value.

### Example 4: Calculating the natural logarithm of an invalid value

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

function to calculate the natural logarithm of an invalid value.

```
SELECT LN(-1);
```

The output is:

```
LN(-1)
------
NULL
```

As you can see, the `LN()`

function returns `NULL`

, because the input value is a negative number, which is not valid for the natural logarithm.

## Related Functions

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

function in Mariadb. They are:

- The
`LOG()`

function: This function is a synonym for the`LN()`

function and can be used interchangeably. For example,`LOG(1)`

is equivalent to`LN(1)`

. - The
`LOG10()`

function: This function returns the logarithm to the base`10`

of a given number. For example,`LOG10(100)`

returns`2`

. - The
`LOG2()`

function: This function returns the logarithm to the base`2`

of a given number. For example,`LOG2(8)`

returns`3`

. - The
`EXP()`

function: This function returns the exponential value of a given number. It is the inverse of the`LN()`

function. For example,`EXP(LN(2))`

returns`2`

.

## Conclusion

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

function works in Mariadb. We have seen the syntax of the function, and some examples of how to use it with different types of numeric expressions. We have also learned about some related functions that can be used with the `LN()`

function. The `LN()`

function is a useful function that can help us calculate the natural logarithm of a number in Mariadb.