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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:

Syntax

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


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