/**
 * Weighted Moving Average (WMA).
 * Computes a linearly-weighted average over a sliding window with weights
 * 1..period (oldest..newest). When `skipna` is true NaNs are ignored
 * within the window; when false a dense fast-path is used.
 * @param source Input series
 * @param period Window length (must be > 0)
 * @param skipna Whether to ignore NaNs inside windows (default: true)
 * @returns Float64Array of WMA values (NaN before window fills)
 */
export declare function wma(source: ArrayLike<number>, period: number, skipna?: boolean): Float64Array;