/**
 * Money Flow Index (MFI).
 * Computes MFI over `period` using typical price and money flow; NaN-aware
 * sliding-window implementation that emits NaN where insufficient valid data exists.
 * @param high High price series
 * @param low Low price series
 * @param close Close price series
 * @param volume Volume series
 * @param period Lookback period (must be > 0)
 * @returns Float64Array of MFI values in [0,100]
 */
export declare function mfi(high: ArrayLike<number>, low: ArrayLike<number>, close: ArrayLike<number>, volume: ArrayLike<number>, period: number): Float64Array;