TheAlgorithms/C-Sharp · error · ArgumentOutOfRangeException

should be greater than zero

Error message

{nameof(stepSize)} should be greater than zero

What it means

ClassicRungeKuttaMethod requires a strictly positive stepSize to advance the RK4 integration; a zero or negative step produces no progress or wrong-direction integration, so it throws ArgumentOutOfRangeException naming stepSize. The message interpolates the parameter name.

Solutions

1. Pass stepSize > 0 and (for this API) ensure xEnd > xStart so the integration proceeds forward.
2. Validate/clamp the step from config before calling.
3. If the interval is shorter than one step, reduce stepSize to fit the interval.

Example fix

// before
var points = solver.ClassicRungeKuttaMethod(0, 1, 1, f, stepSize: 0);
// after
var h = Math.Max(1e-6, configuredStep);
var points = solver.ClassicRungeKuttaMethod(0, 1, 1, f, stepSize: h);

if (stepSize <= 0) throw new ArgumentOutOfRangeException(nameof(stepSize), "stepSize must be > 0");
var points = ClassicRungeKuttaMethod(xStart, xEnd, stepSize, yStart, f);

try { var pts = ClassicRungeKuttaMethod(x0, x1, h, y0, f); }
catch (ArgumentOutOfRangeException ex) when (ex.ParamName == "stepSize") { /* clamp h to a small positive value */ }

When it happens

Trigger: Calling ClassicRungeKuttaMethod with stepSize <= 0, e.g. 0 from a default config or a negative value from a sign error.

Common situations: A step size read from configuration that defaulted to 0, dividing a zero-length interval by a count to compute the step, or a sign flip when supporting backward integration manually.

Related errors

• should be greater than
• Invalid block size
• Not enough space in input array for padding
• Vertex indices must be within valid range.
• k must be at least 1.

AI-assisted analysis of TheAlgorithms/C-Sharp@96e2905cab (2026-09-13). Data as JSON: /api/errors/defba44b9e44b6fe. Report an issue: GitHub.

Appendix: source

Thrown at Algorithms/Numeric/RungeKuttaMethod.cs:37

    /// <param name="function">The right hand side of the differential equation.</param>
    /// <returns>The solution of the Cauchy problem.</returns>
    public static List<double[]> ClassicRungeKuttaMethod(
        double xStart,
        double xEnd,
        double stepSize,
        double yStart,
        Func<double, double, double> function)
    {
        if (xStart >= xEnd)
        {
            throw new ArgumentOutOfRangeException(
                nameof(xEnd),
                $"{nameof(xEnd)} should be greater than {nameof(xStart)}");
        }

        if (stepSize <= 0)
        {
            throw new ArgumentOutOfRangeException(
                nameof(stepSize),
                $"{nameof(stepSize)} should be greater than zero");
        }

        List<double[]> points = [];
        double[] firstPoint = [xStart, yStart];
        points.Add(firstPoint);

        var yCurrent = yStart;
        var xCurrent = xStart;

        while (xCurrent < xEnd)
        {
            var k1 = function(xCurrent, yCurrent);
            var k2 = function(xCurrent + 0.5 * stepSize, yCurrent + 0.5 * stepSize * k1);
            var k3 = function(xCurrent + 0.5 * stepSize, yCurrent + 0.5 * stepSize * k2);
            var k4 = function(xCurrent + stepSize, yCurrent + stepSize * k3);

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