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*, we’ll 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.