/**
 * Pure functions for GPS outlier detection.
 *
 * GPS can produce sudden position jumps ("outliers") due to:
 * - Multipath reflections from buildings
 * - Signal reacquisition after loss
 * - Satellite geometry changes
 *
 * These functions detect and filter outliers by checking if the implied
 * movement speed between positions is physically plausible.
 */
/**
 * Meters per degree of latitude (approximately constant).
 */
export declare const METERS_PER_DEGREE_LAT = 111320;
/**
 * Configuration for outlier detection.
 */
export interface OutlierDetectionConfig {
    /**
     * Maximum plausible speed in m/s for a pedestrian.
     * Positions implying faster movement are considered outliers.
     * @default 10 (~36 km/h, faster than sprinting)
     */
    maxPlausibleSpeed: number;
    /**
     * Minimum time between positions to perform speed check (ms).
     * Avoids division by near-zero for rapid updates.
     * @default 500
     */
    minTimeForSpeedCheck: number;
}
/**
 * Default outlier detection configuration.
 */
export declare const DEFAULT_OUTLIER_CONFIG: OutlierDetectionConfig;
/**
 * A position with timestamp for outlier detection.
 */
export interface TimestampedPosition {
    latitude: number;
    longitude: number;
    timestamp: number;
}
/**
 * Result of outlier detection check.
 */
export interface OutlierCheckResult {
    /** Whether the position is an outlier */
    isOutlier: boolean;
    /** Distance from reference position in meters */
    distance: number;
    /** Time delta from reference in seconds */
    timeDelta: number;
    /** Implied speed in m/s (0 if time delta too small) */
    impliedSpeed: number;
}
/**
 * Calculate distance between two positions in meters.
 *
 * Uses simple equirectangular approximation which is accurate enough
 * for short distances (< 1km) typical of outlier detection.
 *
 * @param lat1 - Reference latitude in degrees
 * @param lon1 - Reference longitude in degrees
 * @param lat2 - New latitude in degrees
 * @param lon2 - New longitude in degrees
 * @returns Distance in meters
 *
 * @example
 * ```ts
 * // About 111m for 0.001° latitude change
 * calculateDistance(43.0, -79.0, 43.001, -79.0); // ~111
 * ```
 */
export declare function calculateDistance(lat1: number, lon1: number, lat2: number, lon2: number): number;
/**
 * Check if a new position is an outlier compared to a reference position.
 *
 * A position is considered an outlier if the implied speed to reach it
 * from the reference position exceeds the maximum plausible speed.
 *
 * @param reference - Reference position (last known good position)
 * @param newPosition - New position to check
 * @param config - Outlier detection configuration
 * @returns Outlier check result with distance, time, and speed info
 *
 * @example
 * ```ts
 * const ref = { latitude: 43.0, longitude: -79.0, timestamp: 0 };
 * const pos = { latitude: 43.001, longitude: -79.0, timestamp: 1000 };
 *
 * // ~111m in 1s = 111 m/s - definitely an outlier
 * checkForOutlier(ref, pos, DEFAULT_OUTLIER_CONFIG);
 * // { isOutlier: true, distance: ~111, timeDelta: 1, impliedSpeed: ~111 }
 * ```
 */
export declare function checkForOutlier(reference: TimestampedPosition, newPosition: TimestampedPosition, config: OutlierDetectionConfig): OutlierCheckResult;
/**
 * Check if a position is an outlier, handling the case where no reference exists.
 *
 * Convenience wrapper that returns false (not an outlier) when reference is undefined,
 * allowing the first position to always be accepted.
 *
 * @param reference - Reference position, or undefined if no previous position
 * @param newPosition - New position to check
 * @param config - Outlier detection configuration
 * @returns Outlier check result, or "not outlier" if no reference
 */
export declare function checkForOutlierSafe(reference: TimestampedPosition | undefined, newPosition: TimestampedPosition, config: OutlierDetectionConfig): OutlierCheckResult;