TheAlgorithms/Python · error · ValueError

Please enter a valid equation.

Error message

Please enter a valid equation.

What it means

Error "Please enter a valid equation." thrown in TheAlgorithms/Python.

Source

Thrown at matrix/cramers_rule_2x2.py:57

        ...
    ValueError: No solution. (Inconsistent system)
    >>> cramers_rule_2x2([0, 0, 6], [0, 0, 3])
    Traceback (most recent call last):
        ...
    ValueError: Both a & b of two equations can't be zero.
    >>> cramers_rule_2x2([1, 2, 3], [1, 2, 3])
    Traceback (most recent call last):
        ...
    ValueError: Infinite solutions. (Consistent system)
    >>> cramers_rule_2x2([0, 4, 50], [0, 3, 99])
    Traceback (most recent call last):
        ...
    ValueError: No solution. (Inconsistent system)
    """

    # Check if the input is valid
    if not len(equation1) == len(equation2) == 3:
        raise ValueError("Please enter a valid equation.")
    if equation1[0] == equation1[1] == equation2[0] == equation2[1] == 0:
        raise ValueError("Both a & b of two equations can't be zero.")

    # Extract the coefficients
    a1, b1, c1 = equation1
    a2, b2, c2 = equation2

    # Calculate the determinants of the matrices
    determinant = a1 * b2 - a2 * b1
    determinant_x = c1 * b2 - c2 * b1
    determinant_y = a1 * c2 - a2 * c1

    # Check if the system of linear equations has a solution (using Cramer's rule)
    if determinant == 0:
        if determinant_x == determinant_y == 0:
            raise ValueError("Infinite solutions. (Consistent system)")
        else:
            raise ValueError("No solution. (Inconsistent system)")

View on GitHub (pinned to f5988cc097)

Solutions

1. Enter both equations in the expected 'ax + by = c' format.

When it happens

Trigger: Thrown at matrix/cramers_rule_2x2.py:57 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/d67e54289f19df5a. Report an issue: GitHub.