/**
 * TA utility helpers for small boolean/rolling operations used by indicators.
 * Includes functions for detecting rising/falling masks and crosses with
 * strict NaN-aware semantics by default.
 */
/**
 * Determine whether global dense optimization should be skipped. Useful for
 * tests that need to exercise NaN-aware code paths by setting
 * `SKIP_DENSE_OPTIMIZATION=true` in the environment.
 * @returns `true` when dense optimizations should be skipped
 */
export declare function shouldSkipDenseOptimization(): boolean;
/**
 * Rising mask: returns a Uint8Array where `1` indicates `source[i]` is
 * strictly greater than the value `length` periods ago (NaN-aware).
 * When `skipna` is true, NaNs are tolerated and preserved; when false a
 * dense fast-path is used (assumes no NaNs).
 * @param source Input numeric series
 * @param length Lookback length (>0)
 * @param skipna Whether to ignore NaNs during computation (default: true)
 * @returns Uint8Array mask with 0/1 values
 */
export declare function rising(source: ArrayLike<number>, length: number, skipna?: boolean): Uint8Array;
/**
 * Falling mask: returns a Uint8Array where `1` indicates `source[i]` is
 * strictly less than the value `length` periods ago (NaN-aware).
 * When `skipna` is true, NaNs are tolerated and preserved; when false a
 * dense fast-path is used (assumes no NaNs).
 * @param source Input numeric series
 * @param length Lookback length (>0)
 * @param skipna Whether to ignore NaNs during computation (default: true)
 * @returns Uint8Array mask with 0/1 values
 */
export declare function falling(source: ArrayLike<number>, length: number, skipna?: boolean): Uint8Array;
/**
 * Test whether series `a` crosses `b` (or a scalar) between the previous and
 * current index. By default uses a symmetric cross test that detects both
 * upward and downward crossings. Comparisons are strict and require non-NaN
 * current and previous values for both operands.
 * @param a Left series
 * @param b Right series or scalar
 * @param test Optional custom comparator receiving (ai, aim1, bi, bim1)
 * @returns Uint8Array mask where 1 indicates a crossing at that index
 */
export declare function cross(a: ArrayLike<number>, b: ArrayLike<number> | number, test?: (ai: number, aim1: number, bi: number, bim1: number) => boolean): Uint8Array;
/**
 * Detect an upward crossover (a crosses above b).
 */
export declare function crossover(a: ArrayLike<number>, b: ArrayLike<number> | number): Uint8Array;
/**
 * Detect a downward crossunder (a crosses below b).
 */
export declare function crossunder(a: ArrayLike<number>, b: ArrayLike<number> | number): Uint8Array;