TheAlgorithms/Java · error · IllegalArgumentException

x and y must be finite numbers.

Error message

x and y must be finite numbers.

What it means

Thrown by CoordinateConverter.cartesianToPolar(double, double) when either x or y is not a finite number (i.e., is NaN, positive infinity, or negative infinity). Finite coordinates are required because Math.sqrt and Math.atan2 produce undefined results for infinite/NaN inputs, and the returned radius/angle would be meaningless.

Source

Thrown at src/main/java/com/thealgorithms/conversions/CoordinateConverter.java:30

 * <p>The class is final and cannot be instantiated.
 */
public final class CoordinateConverter {

    private CoordinateConverter() {
        // Prevent instantiation
    }

    /**
     * Converts Cartesian coordinates to Polar coordinates.
     *
     * @param x the x-coordinate in the Cartesian system; must be a finite number
     * @param y the y-coordinate in the Cartesian system; must be a finite number
     * @return an array where the first element is the radius (r) and the second element is the angle (theta) in degrees
     * @throws IllegalArgumentException if x or y is not a finite number
     */
    public static double[] cartesianToPolar(double x, double y) {
        if (!Double.isFinite(x) || !Double.isFinite(y)) {
            throw new IllegalArgumentException("x and y must be finite numbers.");
        }
        double r = Math.sqrt(x * x + y * y);
        double theta = Math.toDegrees(Math.atan2(y, x));
        return new double[] {r, theta};
    }

    /**
     * Converts Polar coordinates to Cartesian coordinates.
     *
     * @param r the radius in the Polar system; must be non-negative
     * @param thetaDegrees the angle (theta) in degrees in the Polar system; must be a finite number
     * @return an array where the first element is the x-coordinate and the second element is the y-coordinate in the Cartesian system
     * @throws IllegalArgumentException if r is negative or thetaDegrees is not a finite number
     */
    public static double[] polarToCartesian(double r, double thetaDegrees) {
        if (r < 0) {
            throw new IllegalArgumentException("Radius (r) must be non-negative.");
        }

View on GitHub (pinned to fdfb9a395b)

Solutions

1. Filter or reject NaN/Inf at the data ingestion boundary before conversion.
2. Validate with Double.isFinite(x) && Double.isFinite(y) before calling.
3. Substitute a sentinel (e.g., 0.0) or skip the conversion if the input is non-finite.

Example fix

// before
double[] polar = CoordinateConverter.cartesianToPolar(Double.NaN, 5.0);

// after
if (!Double.isFinite(x) || !Double.isFinite(y)) {
    throw new IllegalArgumentException("coordinates must be finite");
}
double[] polar = CoordinateConverter.cartesianToPolar(x, y);

if (!Double.isFinite(x) || !Double.isFinite(y)) {
    throw new IllegalArgumentException("coordinates must be finite");
}
double[] polar = CoordinateConverter.cartesianToPolar(x, y);

static boolean areFiniteCoordinates(double x, double y) {
    return Double.isFinite(x) && Double.isFinite(y);
}

try {
    double[] polar = CoordinateConverter.cartesianToPolar(x, y);
} catch (IllegalArgumentException e) {
    throw new DomainException("Non-finite coordinates", e);
}

When it happens

Trigger: Passing Double.NaN, Double.POSITIVE_INFINITY, or Double.NEGATIVE_INFINITY as x or y. Passing the result of an upstream computation that overflowed or divided by zero in floating point. Reading unparseable numeric input that defaulted to NaN.

Common situations: Sensor data with dropout values represented as NaN/Inf. Config or input parsing failures yielding NaN. Mathematical operations that can overflow (large exponents, divisions).

Related errors

• Slope and intercept must be valid numbers.
• Radius (r) must be non-negative.
• For input string: {}
• Input cannot be null
• Invalid Base64 input length; must be multiple of 4

AI-assisted analysis of TheAlgorithms/Java@fdfb9a395b (2026-08-13). Data as JSON: /api/errors/d55be0e77030dd45. Report an issue: GitHub.