# How can I use e (Eulers number) and power operation in python 2.7

## How can I use e (Eulers number) and power operation in python 2.7

You can use ** exp(x)** function of math library, which is same as

`e^x`

. Hence you may write your code as:```
import math
x.append(1 - math.exp( -0.5 * (value1*value2)**2))
```

I have modified the equation by replacing `1/2`

as `0.5`

. Else for Python *<2.7*, well have to explicitly type cast the division value to `float`

because Python round of the result of division of two `int`

as integer. For example: `1/2`

gives `0`

in python 2.7 and below.

Pythons power operator is `**`

and Eulers number is `math.e`

, so:

```
from math import e
x.append(1-e**(-value1**2/2*value2**2))
```

#### How can I use e (Eulers number) and power operation in python 2.7

Just saying: `numpy`

has this too. So no need to import `math`

if you already did `import numpy as np`

:

```
>>> np.exp(1)
2.718281828459045
```