pi in Python – Using Math Module and Leibniz Formula to Get Value of pi

To get the value of pi in Python, the easiest way is use the Python math module constant pi. math.pi returns the value 3.141592653589793.

import math

print(math.pi) 

#Output: 
3.141592653589793

You can also use the numpy module to get the value of pi.

import numpy as np

print(np.pi) 

#Output: 
3.141592653589793

In Python, we can easily get the value of pi for use in trigonometry
with the Python math module.

For example, let’s say we want to find the sine of a number. The Python sin() function takes a number in radians and then finds the sine of the number.

To find the sine of a number, we can use pi to make our lives easy.

To get the value of pi in your Python code, you just need to import the math module and call it as shown below.

import math

print(math.pi)

Then, if you want to use it like in our example with finding the sine of a number, you can use the pi constant in the following way.

import math

print(math.sin(math.pi/3))

#Output:
0.8660254037844386

Using numpy to Get Value of pi in Python

Another module which has the mathematical constant pi is numpy.

You can do the following to get the value of pi with numpy.

import numpy as np

print(np.pi) 

#Output: 
3.141592653589793

Finding pi in Python Without the Math Module

With the Python math module, we can get a pretty good estimate of pi.

However, you may want to calculate pi for yourself without the math module to get more digits and a more accurate representation of pi.

In this case, we can use the Leibniz formula.

Below is a function which will let you calculate pi to more digits than just 15 digits like in the math module. In this example, we use the Python decimal module to calculate pi to 100 digits.

import decimal
import math

decimal.getcontext().prec = 100

def leibniz(n):
    pi = decimal.Decimal(1)
    for i in range (1,n):
        pi += ((-1) ** i ) * (decimal.Decimal(1) / (2 * i + 1))
    return pi * 4

print(leibniz(1000))

#Output: 
Decimal('3.140592653839792925963596502869395970451389330779724489367457783541907931239747608265172332007670214')

Hopefully this article has been helpful for you to understand how to find the value of pi from the Python math module.