TheAlgorithms/Java · error · IllegalArgumentException

Damping factor must be between 0 and 1

Error message

Damping factor must be between 0 and 1

What it means

Thrown by PageRank.validateInputParameters when dampingFactor is outside [0, 1]. The damping factor weights the random-surfer contribution in the PageRank formula; values below 0 or above 1 break the probabilistic model and the convergence of the iteration.

Source

Thrown at src/main/java/com/thealgorithms/others/PageRank.java:188

        }

        return pageRankValues.clone();
    }

    /**
     * Validates input parameters for PageRank calculation
     *
     * @param totalNodes    the total number of nodes
     * @param dampingFactor the damping factor
     * @param iterations    number of iterations
     * @throws IllegalArgumentException if parameters are invalid
     */
    private void validateInputParameters(int totalNodes, double dampingFactor, int iterations) {
        if (totalNodes < 1 || totalNodes > MAX_NODES) {
            throw new IllegalArgumentException("Total nodes must be between 1 and " + MAX_NODES);
        }
        if (dampingFactor < 0 || dampingFactor > 1) {
            throw new IllegalArgumentException("Damping factor must be between 0 and 1");
        }
        if (iterations < 1) {
            throw new IllegalArgumentException("Iterations must be at least 1");
        }
    }

    /**
     * Initializes PageRank values for all nodes
     *
     * @param totalNodes      the total number of nodes
     * @param initialPageRank the initial PageRank value
     * @param verbose         whether to print output
     */
    private void initializePageRanks(int totalNodes, double initialPageRank, boolean verbose) {
        for (int i = 1; i <= totalNodes; i++) {
            pageRankValues[i] = initialPageRank;
        }

View on GitHub (pinned to fdfb9a395b)

Solutions

1. Pass dampingFactor as a fraction in [0, 1] (the classic default is 0.85).
2. If your input is a percentage, divide by 100 before passing.
3. Clamp the value to [0, 1] at the boundary.
4. Validate at config-load time so the error surfaces with full context.

Example fix

// before
pageRank.calc(totalNodes, 85, iterations); // 85 > 1 -> throws

// after
double damping = percent / 100.0; // e.g. 85 -> 0.85
pageRank.calc(totalNodes, damping, iterations);

double damping = Math.max(0.0, Math.min(1.0, dampingFactor));
pageRank.calc(totalNodes, damping, iterations);

public static boolean isValidDamping(double d) {
    return d >= 0.0 && d <= 1.0;
}

try {
    pageRank.calc(total, damping, iters);
} catch (IllegalArgumentException e) {
    if (e.getMessage().contains("Damping")) {
        pageRank.calc(total, 0.85, iters); // classic default
    } else throw e;
}

When it happens

Trigger: Triggering a calculation that calls validateInputParameters with dampingFactor < 0 or dampingFactor > 1; passing a percentage (e.g. 85) instead of a fraction (0.85).

Common situations: Supplying a percentage (85) instead of a fraction (0.85); a slider/config yielding an out-of-range value; defaulting an unset parameter to 0 and then nudging it negative.

Related errors

• Number of nodes must be between 1 and + MAX_NODES
• Node index out of bounds
• Total nodes must be between 1 and + MAX_NODES
• Iterations must be at least 1
• Incorrect length parameters: minLength must be <= maxLength

AI-assisted analysis of TheAlgorithms/Java@fdfb9a395b (2026-08-13). Data as JSON: /api/errors/27458acd279e931f. Report an issue: GitHub.