maths.pell_number

Functions

pell_number_iterative(→ int)	This function returns the subscript-th Pell number iteratively, where
pell_number_recursive(→ int)	This function calculates the subscript-th Pell number recursively. Due to

Module Contents

maths.pell_number.pell_number_iterative(subscript: int) → int

This function returns the subscript-th Pell number iteratively, where subscript is a non-negative integer. Pell numbers are defined by the recurrence relation:

P_0 = 0, P_1 = 1, P_n = 2 * P_(n-1) + P_(n-2)

https://en.wikipedia.org/wiki/Pell_number https://oeis.org/A000129

>>> pell_number_iterative(0)
0
>>> pell_number_iterative(1)
1
>>> pell_number_iterative(12)
13860
>>> pell_number_iterative("1")
Traceback (most recent call last):
    ...
ValueError: The input must be an integer.
>>> pell_number_iterative(-1)
Traceback (most recent call last):
    ...
ValueError: The input number must be non-negative.

maths.pell_number.pell_number_recursive(subscript: int) → int

This function calculates the subscript-th Pell number recursively. Due to its recursive nature, this function grows exponentially with subscript. For large values of subscript, use pell_number_iterative instead.

>>> pell_number_recursive(0)
0
>>> pell_number_recursive(1)
1
>>> pell_number_recursive(12)
13860
>>> pell_number_recursive("1")
Traceback (most recent call last):
    ...
ValueError: The input must be an integer.
>>> pell_number_recursive(-1)
Traceback (most recent call last):
    ...
ValueError: The input number must be non-negative.