Python/electronics/resistor_equivalence.py

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# https://byjus.com/equivalent-resistance-formula/
from __future__ import annotations
def resistor_parallel(resistors: list[float]) -> float:
"""
Req = 1/ (1/R1 + 1/R2 + ... + 1/Rn)
>>> resistor_parallel([3.21389, 2, 3])
0.8737571620498019
>>> resistor_parallel([3.21389, 2, -3])
Traceback (most recent call last):
...
ValueError: Resistor at index 2 has a negative or zero value!
>>> resistor_parallel([3.21389, 2, 0.000])
Traceback (most recent call last):
...
ValueError: Resistor at index 2 has a negative or zero value!
"""
first_sum = 0.00
index = 0
for resistor in resistors:
if resistor <= 0:
msg = f"Resistor at index {index} has a negative or zero value!"
raise ValueError(msg)
first_sum += 1 / float(resistor)
index += 1
return 1 / first_sum
def resistor_series(resistors: list[float]) -> float:
"""
Req = R1 + R2 + ... + Rn
Calculate the equivalent resistance for any number of resistors in parallel.
>>> resistor_series([3.21389, 2, 3])
8.21389
>>> resistor_series([3.21389, 2, -3])
Traceback (most recent call last):
...
ValueError: Resistor at index 2 has a negative value!
"""
sum_r = 0.00
index = 0
for resistor in resistors:
sum_r += resistor
if resistor < 0:
msg = f"Resistor at index {index} has a negative value!"
raise ValueError(msg)
index += 1
return sum_r
if __name__ == "__main__":
import doctest
doctest.testmod()