TheAlgorithms/Python · error · ValueError

Capacitor at index {index} has a negative or zero value!

Error message

Capacitor at index {index} has a negative or zero value!

What it means

Thrown by capacitor_series() in electronics/capacitor_equivalence.py when any element of the capacitors iterable is <= 0. The series-equivalent formula computes 1/C_eq = sum(1/C_i), which is undefined for zero and physically meaningless for negative capacitance, so the library rejects the input up front. The message includes the offending index so you can locate the bad element.

Source

Thrown at electronics/capacitor_equivalence.py:45

    """
    Ceq = 1/ (1/C1 + 1/C2 + ... + 1/Cn)
    >>> capacitor_series([5.71389, 12, 3])
    1.6901062252507735
    >>> capacitor_series([5.71389, 12, -3])
    Traceback (most recent call last):
        ...
    ValueError: Capacitor at index 2 has a negative or zero value!
    >>> capacitor_series([5.71389, 12, 0.000])
    Traceback (most recent call last):
        ...
    ValueError: Capacitor at index 2 has a negative or zero value!
    """

    first_sum = 0.0
    for index, capacitor in enumerate(capacitors):
        if capacitor <= 0:
            msg = f"Capacitor at index {index} has a negative or zero value!"
            raise ValueError(msg)
        first_sum += 1 / capacitor
    return 1 / first_sum


if __name__ == "__main__":
    import doctest

    doctest.testmod()

View on GitHub (pinned to f5988cc097)

Solutions

1. Inspect the index reported in the message and fix or remove that element before calling capacitor_series.
2. Filter non-positive values only if they are known to be sentinel/missing data: [c for c in capacitors if c > 0].
3. Add a validation step upstream where the values enter your program (parser, config loader) so 0/negative never reaches the library.

Example fix

# before
capacitor_series([5.71389, 12, 0.000])  # ValueError

# after
capacitor_series([5.71389, 12, 10.0])

def valid_capacitors(values):
    return all(isinstance(c, (int, float)) and c > 0 for c in values)

if not valid_capacitors(capacitors):
    bad = [i for i, c in enumerate(capacitors) if c <= 0]
    raise ValueError(f"non-positive capacitor at indices {bad}")
result = capacitor_series(capacitors)

try:
    ceq = capacitor_series(capacitors)
except ValueError as e:
    if "negative or zero value" in str(e):
        # strip/repair bad elements, then retry once with clean data
        raise
    raise

When it happens

Trigger: capacitor_series([5.71389, 12, 0.000]) or any call where an element is 0 or negative, e.g. capacitor_series([-4.7, 10]). Passing an empty-derived value or a computed list containing 0.0 also triggers it.

Common situations: Feeding parsed component values from a datasheet/CSV where a missing entry defaulted to 0; unit-conversion bugs producing 0 (e.g. uF vs F mix-up); test fixtures generated with range(0) style values.

Related errors

• You cannot supply more or less than 2 values
• Source voltage must be positive.
• Source voltage must be positive.
• Donor concentration should be positive
• Acceptor concentration should be positive

AI-assisted analysis of TheAlgorithms/Python@f5988cc097 (2026-08-14). Data as JSON: /api/errors/3e3e10f8b374f0ea. Report an issue: GitHub.