TheAlgorithms/Python · error · ValueError

Insufficient initial points information.

Error message

Insufficient initial points information.

What it means

Error "Insufficient initial points information." thrown in TheAlgorithms/Python.

Source

Thrown at maths/numerical_analysis/adams_bashforth.py:81

            for x0, x1 in zip(self.x_initials, self.x_initials[1:])
        ):
            raise ValueError("x-values must be equally spaced according to step size.")

    def step_2(self) -> np.ndarray:
        """
        >>> def f(x, y):
        ...     return x
        >>> AdamsBashforth(f, [0, 0.2], [0, 0], 0.2, 1).step_2()
        array([0.  , 0.  , 0.06, 0.16, 0.3 , 0.48])

        >>> AdamsBashforth(f, [0, 0.2, 0.4], [0, 0, 0.04], 0.2, 1).step_2()
        Traceback (most recent call last):
            ...
        ValueError: Insufficient initial points information.
        """

        if len(self.x_initials) != 2 or len(self.y_initials) != 2:
            raise ValueError("Insufficient initial points information.")

        x_0, x_1 = self.x_initials[:2]
        y_0, y_1 = self.y_initials[:2]

        n = int((self.x_final - x_1) / self.step_size)
        y = np.zeros(n + 2)
        y[0] = y_0
        y[1] = y_1

        for i in range(n):
            y[i + 2] = y[i + 1] + (self.step_size / 2) * (
                3 * self.func(x_1, y[i + 1]) - self.func(x_0, y[i])
            )
            x_0 = x_1
            x_1 += self.step_size

        return y

View on GitHub (pinned to f5988cc097)

Solutions

1. Provide at least as many initial (x, y) points as the method's order requires.
2. Use a single-step method (e.g. Runge-Kutta) to generate the missing starting points.

When it happens

Trigger: Thrown at maths/numerical_analysis/adams_bashforth.py:81 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/f88c56cebe1b9c16. Report an issue: GitHub.