# C++ Math log()

The function is used to find the natural logarithm (base-e logarithm) of a given number.

## Mathematically:

Suppose 'x' is a given number:

## Parameter

x: It is the value whose natural logarithm is to be calculated.

## Return value

Following are the return values of a given number:

Parameter(x) Return value
x>1 Positive
x=1 0
1>x>0 Negative
x=0 -infinty
x<0 Not a Number(nan)

## Example 1

Let's see a simple example when the value of x is 1.

Output:

```Value of x is : 1
Log value of x is : 0
```

In this example, the value of x is 1. Therefore, the function log() returns the positive value i.e 0.

## Example 2

Let's see another simple example

Output:

```Value of x is : 3
Log value of x is : 1.09861
```

In this example, the value of x is 3. Therefore, the function log() returns the positive value i.e 1.09861

## Example 3

Let's see a simple example when the value of x is -0.5.

Output:

```Value of x is : -0.5
Log value of x is : nan
```

In this example, value of x is -0.5. Therefore, the function log() returns the Not a Number(nan).

## Example 4

Let's see a simple example when the value of x is 0.

Output:

```clValue of x is : 0
Log value of x is : -inf
```

In this example, value of x is -1. Therefore, the function log() returns nan(Not a Number).

## Example 5

Let's see a simple example when the value of x is 0.8.

Output:

```Value of x is : 0.8
Log value of x is : -0.223144
```

In this example, value of x is 0.8. Therefore, the function log() returns the negative value i.e -0.22

Next TopicC++ Math Functions   