/**
 * Returns the average of an array of numbers
 * @param arr
 * @category Array
 * @example
 * ```ts
 * average([1, 2, 3, 4]) // 2.5
 * ```
 */
export declare function average(arr: number[]): number;
/**
 * Returns the average of an array of numbers
 * @param arr
 * @category Array
 * @example
 * ```ts
 * avg([1, 2, 3, 4]) // 2.5
 * ```
 */
export declare function avg(arr: number[]): number;
/**
 * Returns the median of an array of numbers
 * @param arr
 * @category Array
 * @example
 * ```ts
 * median([1, 2, 3, 4]) // 2.5
 * ```
 */
export declare function median(arr: number[]): number;
/**
 * Returns the mode of an array of numbers
 * @param arr
 * @category Array
 * @example
 * ```ts
 * mode([1, 2, 3, 4]) // 1
 * mode([1, 2, 2, 3, 4]) // 2
 * mode([1, 2, 2, 3, 3, 4]) // 2
 * mode([1, 2, 2, 3, 3, 4, 4]) // 2
 * mode([1, 2, 2, 3, 3, 4, 4, 4]) // 4
 * ```
 */
export declare function mode(arr: number[]): number;
/**
 * Returns the sum of an array of numbers
 * @param array
 * @category Array
 * @example
 * ```ts
 * sum([1, 2, 3, 4]) // 10
 * ```
 */
export declare function sum(array: readonly number[]): number;
/**
 * Returns the product of an array of numbers.
 *
 * Throws when an intermediate product exceeds `Number.MAX_SAFE_INTEGER` —
 * silently returning a precision-lossy float made downstream comparisons
 * (e.g. inventory totals, distance calcs) lie without any signal that
 * the result was unreliable.
 *
 * @param array
 * @category Array
 * @example
 * ```ts
 * product([1, 2, 3, 4]) // 24
 * ```
 */
export declare function product(array: readonly number[]): number;
/**
 * Returns the minimum value of an array of numbers
 * @param array
 * @category Array
 * @example
 * ```ts
 * min([1, 2, 3, 4]) // 1
 * min([1, 2, 3, 4, -1]) // -1
 * ```
 */
export declare function min(array: readonly number[]): number;
/**
 * Returns the maximum value of an array of numbers
 * @param array
 * @category Array
 * @example
 * ```ts
 * max([1, 2, 3, 4]) // 4
 * max([1, 2, 3, 4, -1]) // 4
 * ```
 */
export declare function max(array: readonly number[]): number;
/**
 * Returns the range of an array of numbers
 * @param array
 * @category Array
 * @example
 * ```ts
 * range([1, 2, 3, 4]) // 3
 * range([1, 2, 3, 4, -1]) // 5
 * range([1, 2, 3, 4, -1, 10]) // 11
 * ```
 */
export declare function range(array: readonly number[]): number;
/**
 * Returns the variance of an array of numbers
 * @param array
 * @category Array
 * @example
 * ```ts
 * variance([1, 2, 3, 4]) // 1.25
 * ```
 * @see https://en.wikipedia.org/wiki/Variance
 */
export declare function variance(array: number[]): number;
/**
 * Returns the standard deviation of an array of numbers
 * @param array
 * @category Array
 * @example
 * ```ts
 * standardDeviation([1, 2, 3, 4]) // 1.118033988749895
 * ```
 * @see https://en.wikipedia.org/wiki/Standard_deviation
 * @see https://stackoverflow.com/questions/7343890/standard-deviation-javascript
 */
export declare function standardDeviation(array: number[]): number;
/**
 * Returns the z-score of a number in an array of numbers
 * @param array
 * @param num
 * @category Array
 * @example
 * ```ts
 * zScore([1, 2, 3, 4], 2) // 0
 * zScore([1, 2, 3, 4], 3) // 0.7071067811865475
 * ```
 * @see https://en.wikipedia.org/wiki/Standard_score
 */
export declare function zScore(array: number[], num: number): number;
/**
 * Returns the percentile of a number in an array of numbers
 * @param array
 * @param num
 * @category Array
 * @example
 * ```ts
 * percentile([1, 2, 3, 4], 2) // 0.25
 * percentile([1, 2, 3, 4], 3) // 0.75
 * ```
 * @see https://en.wikipedia.org/wiki/Percentile
 */
export declare function percentile(array: number[], num: number): number;
/**
 * Returns the interquartile range of an array of numbers
 * @param array
 * @category Array
 * @example
 * ```ts
 * interquartileRange([1, 2, 3, 4]) // 1.5
 * ```
 * @see https://en.wikipedia.org/wiki/Interquartile_range
 * @see https://stackoverflow.com/questions/48719873/how-to-calculate-interquartile-range-in-javascript
 */
export declare function interquartileRange(array: number[]): number;
/**
 * Returns the covariance of two arrays of numbers
 * @param array1
 * @param array2
 * @category Array
 * @example
 * ```ts
 * covariance([1, 2, 3, 4], [1, 2, 3, 4]) // 1.25
 * covariance([1, 2, 3, 4], [4, 3, 2, 1]) // -1.25
 * ```
 */
export declare function covariance(array1: number[], array2: number[]): number;