Recursive factorial in Python
problem
Recursion is a type of repetition. In this post, we calculate factorial using recursion. Factorial is a mathematical term given with the following formula:
n! = n × (n – 1)!
SOLUTION
Due to the recursive nature of the formula, it is easier to implement it using recursion as follows:
def fact(n):
if n==0:
return 1
else:
return n * fact(n-1)
running - import in the interpreter
Start your terminal and execute the following:
python3
Import the factorial.py by specifying only the filetitle without the .py
import factorial
The factorial.py file needs to be located in the same directory where the interpreter started. If successful, we can now execute the fact function by appending it to the imported name:
factorial.fact(5) #calculate 5!
output
Looks correct. 5! = 120
conclusion
In this post we saw how to simply write the recursive factorial function. Save it in a file (e.g. factorial.py) and then import it in the Python interpreter and execute the fact function. We could have also extended the program and use the Python main function for testing it out.
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Ellion
Professional IT consultant, writer, programmer enthusiast interested in all sorts of coding.
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