| 1 | // Small helpers for numbers. |
| 2 | /** Returns the sum of a and b. */ |
| 3 | function add(a, b) { |
| 4 | return a + b; |
| 5 | } |
| 6 | |
| 7 | /** Returns the product of a and b. */ |
| 8 | function multiply(a, b) { |
| 9 | return a * b; |
| 10 | } |
| 11 | |
| 12 | /** Returns the non-negative remainder of a divided by b; throws RangeError when b is 0. */ |
| 13 | function mod(a, b) { |
| 14 | if (b === 0) { |
| 15 | throw new RangeError("mod by zero"); |
| 16 | } |
| 17 | return ((a % b) + Math.abs(b)) % Math.abs(b); |
| 18 | } |
| 19 | |
| 20 | /** Returns a minus b. */ |
| 21 | function subtract(a, b) { |
| 22 | return a - b; |
| 23 | } |
| 24 | |
| 25 | /** Returns a divided by b; throws a RangeError when b is 0. */ |
| 26 | function divide(a, b) { |
| 27 | if (b === 0) { |
| 28 | throw new RangeError("Division by zero"); |
| 29 | } |
| 30 | return a / b; |
| 31 | } |
| 32 | |
| 33 | /** Returns base raised to the whole-number exponent; throws a RangeError if exponent is negative. */ |
| 34 | function power(base, exponent) { |
| 35 | if (exponent < 0) { |
| 36 | throw new RangeError("exponent must not be negative"); |
| 37 | } |
| 38 | let result = 1; |
| 39 | for (let i = 0; i < exponent; i++) { |
| 40 | result *= base; |
| 41 | } |
| 42 | return result; |
| 43 | } |
| 44 | |
| 45 | /** Returns the average of numbers; throws a TypeError if the array is empty. */ |
| 46 | function mean(numbers) { |
| 47 | if (numbers.length === 0) { |
| 48 | throw new TypeError("numbers must not be empty"); |
| 49 | } |
| 50 | return numbers.reduce((sum, n) => sum + n, 0) / numbers.length; |
| 51 | } |
| 52 | |
| 53 | /** Returns the middle value of numbers (the average of the two middle values when the length is even); throws a TypeError if the array is empty. */ |
| 54 | function median(numbers) { |
| 55 | if (numbers.length === 0) { |
| 56 | throw new TypeError("numbers must not be empty"); |
| 57 | } |
| 58 | const sorted = [...numbers].sort((a, b) => a - b); |
| 59 | const mid = Math.floor(sorted.length / 2); |
| 60 | return sorted.length % 2 === 0 ? (sorted[mid - 1] + sorted[mid]) / 2 : sorted[mid]; |
| 61 | } |
| 62 | |
| 63 | /** Returns the population standard deviation of numbers; throws a TypeError if the array is empty. */ |
| 64 | function standard_deviation(numbers) { |
| 65 | const avg = mean(numbers); |
| 66 | const variance = numbers.reduce((sum, n) => sum + (n - avg) ** 2, 0) / numbers.length; |
| 67 | return Math.sqrt(variance); |
| 68 | } |
| 69 | |
| 70 | /** Returns value limited to the range [min, max]; throws a RangeError if min is greater than max. */ |
| 71 | function clamp(value, min, max) { |
| 72 | if (min > max) { |
| 73 | throw new RangeError("min must not be greater than max"); |
| 74 | } |
| 75 | return Math.min(Math.max(value, min), max); |
| 76 | } |
| 77 | |
| 78 | module.exports = { add, multiply, subtract, divide, mod, power, mean, median, standard_deviation, clamp }; |