# PHP | exp() Function

• Last Updated : 09 Mar, 2018

Euler’s Number or commonly known as e is a very popular irrational number which approximates to 2.718281828, and is one of the most important mathematical constants. e is the base of the Natural system of logarithms. The exponential values are broadly used in many occasions such as Compound Interests, Bernoulli trials, Normal Distribution, Calculus and many more.

The exp() function is used to calculate e raised to the power of the given argument.

Syntax:

```float exp(\$power)
```

Parameters: The function takes a single parameter \$power which defines the power e has to be raised to.

Return Type: This function returns the value of e raised to the power of the given argument as a float.

Examples:

```Input :  \$power = 0;
Output : 1

Input : \$power = 1;
Output : 2.718281828459
```

Below program illustrates the working of exp() in PHP:

 ``

Output:

```e^-2 = 0.13533528323661
e^-1 = 0.36787944117144
e^0 = 1
e^1 = 2.718281828459
e^2 = 7.3890560989307
```

Important points to note:

• exp() function is a very popular method to calculate exponential values.
• log() function is the functional counterpart of exp().
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