TheAlgorithms/Python · error · ValueError

Length of initial roots must match the degree of the polynom

Error message

Length of initial roots must match the degree of the polynomial.

What it means

Error "Length of initial roots must match the degree of the polynomial." thrown in TheAlgorithms/Python.

Source

Thrown at maths/numerical_analysis/weierstrass_method.py:73

    if degree < 1:
        raise ValueError("Degree of the polynomial must be at least 1.")

    if roots is None:
        # Use perturbed complex roots of unity as initial guesses
        rng = np.random.default_rng()
        roots = np.array(
            [
                np.exp(2j * np.pi * i / degree) * (1 + 1e-3 * rng.random())
                for i in range(degree)
            ],
            dtype=np.complex128,
        )

    else:
        roots = np.asarray(roots, dtype=np.complex128)
        if roots.shape[0] != degree:
            raise ValueError(
                "Length of initial roots must match the degree of the polynomial."
            )

    for _ in range(max_iter):
        # Construct the product denominator for each root
        denominator = np.array([root - roots for root in roots], dtype=np.complex128)
        np.fill_diagonal(denominator, 1.0)  # Avoid zero in diagonal
        denominator = np.prod(denominator, axis=1)

        # Evaluate polynomial at each root
        numerator = polynomial(roots).astype(np.complex128)

        # Compute update and clip to prevent overflow
        delta = numerator / denominator
        delta = np.clip(delta, -1e10, 1e10)
        roots -= delta

    return roots

View on GitHub (pinned to f5988cc097)

Solutions

1. Provide exactly one initial root guess per polynomial degree.

When it happens

Trigger: Thrown at maths/numerical_analysis/weierstrass_method.py:73 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of TheAlgorithms/Python@f5988cc097 (2026-08-14). Data as JSON: /api/errors/fb094867662c0f5d. Report an issue: GitHub.