/**
 * Compute the (possibly weighted) mean of `source`.
 * By default NaNs are skipped (`skipna=true`). When `weights` are provided they
 * must match `source` length and the function computes the weighted mean.
 * A dense fast-path is used when the global optimization allows it.
 * @param source Input array
 * @param options Optional `{ weights?, skipna? }`
 * @returns Mean value or NaN when undefined
 */
export declare function mean(source: ArrayLike<number>, options?: {
    weights?: ArrayLike<number>;
    skipna?: boolean;
}): number;
/**
 * Rolling mean (moving average) over a sliding window of length `period`.
 * When `skipna` is true, NaNs inside windows are ignored; windows with no
 * valid values produce NaN. A fast dense path is used when no NaNs.
 * @param source Input array
 * @param period Window length (>0)
 * @param skipna Whether to ignore NaNs (default: true)
 * @returns Float64Array of rolling means
 */
export declare function rollmean(source: ArrayLike<number>, period: number, skipna?: boolean): Float64Array;
/**
 * Harmonic mean (optionally weighted). Values must be positive; NaNs are
 * ignored when `skipna` is true. Returns NaN when no valid values.
 * @param source Input array
 * @param options Optional `{ weights?, skipna? }`
 * @returns Harmonic mean or NaN
 */
export declare function hmean(source: ArrayLike<number>, options?: {
    weights?: ArrayLike<number>;
    skipna?: boolean;
}): number;
/**
 * Geometric mean (optionally weighted). Values must be positive; NaNs are
 * ignored when `skipna` is true. Returns NaN when no valid values.
 * @param source Input array
 * @param options Optional `{ weights?, skipna? }`
 * @returns Geometric mean or NaN
 */
export declare function gmean(source: ArrayLike<number>, options?: {
    weights?: ArrayLike<number>;
    skipna?: boolean;
}): number;
/**
 * Mean absolute deviation from the mean. When `skipna` is true NaNs are
 * ignored. Returns NaN when the input contains no valid values.
 * @param source Input array
 * @param options Optional `{ skipna? }`
 * @returns Mean absolute deviation or NaN
 */
export declare function mad(source: ArrayLike<number>, skipna?: boolean): number;