TheAlgorithms/C-Sharp · error · ArgumentException

Only for num >= 0

Error message

Only for num >= 0

What it means

GaussJordanElimination.Solve(matrix) solves a linear system via Gauss-Jordan elimination on an augmented n x (n+1) matrix. Before solving it calls CanMatrixBeUsed, which requires the matrix to be non-empty and shaped n x (n+1); otherwise it throws ArgumentException 'Please use a n*(n+1) matrix with Length > 0.'

Solutions

1. Build the augmented matrix: for a system A*x = b, create an n x (n+1) array where column n holds b.
2. Check the matrix is non-empty (GetLength(0) > 0 and GetLength(1) == GetLength(0) + 1) before calling Solve.
3. Inspect CanMatrixBeUsed's shape rules and validate input where it is constructed, e.g. after parsing.

Example fix

// before
var solver = new GaussJordanElimination();
solver.Solve(a); // a is n x n: throws
// after
int n = a.GetLength(0);
var augmented = new double[n, n + 1];
for (int i = 0; i < n; i++)
{
    for (int j = 0; j < n; j++) augmented[i, j] = a[i, j];
    augmented[i, n] = b[i];
}
solver.Solve(augmented);

bool usable = matrix != null
    && matrix.GetLength(0) > 0
    && matrix.GetLength(1) == matrix.GetLength(0) + 1;
if (!usable)
    throw new ArgumentException("Solve requires a non-empty n x (n+1) augmented matrix");

static bool IsAugmentedMatrix(double[,] m) =>
    m != null && m.GetLength(0) > 0 && m.GetLength(1) == m.GetLength(0) + 1;

try
{
    var ok = solver.Solve(matrix);
}
catch (ArgumentException ex) when (ex.Message.Contains("n*(n+1)"))
{
    // rebuild augmented matrix or reject input
}

When it happens

Trigger: Passing a non-augmented n x n coefficient matrix instead of n x (n+1); passing an empty 0-length array (RowCount becomes 0); passing a rectangular matrix whose column count is not rows + 1.

Common situations: Forgetting to append the constants column (b) to the coefficient matrix; loading a system from CSV without the RHS column; constructing the array with new double[0,0] when the input was empty or parsing failed.

Understand the failure class

Background: Tensor shape mismatch errors ("must have shape", "expected shape ... got ..."): when tensor dimensions disagree with what an op or layer was told to expect — this error's family across 6 libraries.

Related errors

• Source matrix is not square shaped.
• Matrix of equation coefficients is not square shaped.
• The source matrix is not square-shaped.
• Invalid parameter settings for Ascon Hash
• Cash flows list cannot be empty

AI-assisted analysis of TheAlgorithms/C-Sharp@96e2905cab (2026-09-13). Data as JSON: /api/errors/3f1781f38996e10a. Report an issue: GitHub.

Appendix: source

Thrown at Algorithms/Numeric/Factorial.cs:22

///     The factorial of a positive integer n, denoted by n!,
///     is the product of all positive integers less than or equal to n.
/// </summary>
public static class Factorial
{
    /// <summary>
    ///     Calculates factorial of a integer number.
    /// </summary>
    /// <param name="inputNum">Integer Input number.</param>
    /// <returns>Factorial of integer input number.</returns>
    public static BigInteger Calculate(int inputNum)
    {
        // Convert integer input to BigInteger
        BigInteger num = new BigInteger(inputNum);

        // Don't calculate factorial if input is a negative number.
        if (BigInteger.Compare(num, BigInteger.Zero) < 0)
        {
            throw new ArgumentException("Only for num >= 0");
        }

        // Factorial of numbers greater than 0.
        BigInteger result = BigInteger.One;

        for (BigInteger i = BigInteger.One; BigInteger.Compare(i, num) <= 0; i = BigInteger.Add(i, BigInteger.One))
        {
            result = BigInteger.Multiply(result, i);
        }

        return result;
    }
}

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