Setting Precision in Python Using Decimal Module

The decimal module in Python can be used to set the precise value of a number. The default value of the Decimal module is up to 28 significant figures. However, it can be changed using getcontext().prec method.

The below program demonstrates the use of decimal module by computing the square root of 2 numbers up to the default the number of places.

Python3

# Import required modules
import decimal

# Create decimal object
ob1 = decimal.Decimal(5).sqrt()
ob2 = decimal.Decimal(7).sqrt()

# Display value
print(ob1)
print(ob2)

Output

2.236067977499789696409173669
2.645751311064590590501615754

We can set the precision up to n significant figure. The decimal.getcontext().prec has to be declared in the global scope such that all the decimal objects can have n significant figures.

Python3

# Import required module
import decimal

# Set precision to a fixed value
decimal.getcontext().prec = 6

# Create Decimal object
ob1 = decimal.Decimal(5).sqrt()
ob2 = decimal.Decimal(7).sqrt()

# Display value up to 6 significant figures
print(ob1)
print(ob2)

Output

2.23607
2.64575