/**
 * Hull Moving Average (HMA).
 * Computes a lower-lag smoothing by combining WMAs at different lengths
 * and then applying a final WMA on the derived series. Pine-compatible
 * and NaN-aware: NaNs propagate where insufficient valid samples exist.
 * @param source Input series
 * @param period Window length (must be > 0)
 * @returns Float64Array of HMA values (NaN where undefined)
 */
export declare function hma(source: ArrayLike<number>, period: number): Float64Array;