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| Add math helpers, tests and checks | 1 | // Small helpers for numbers. |
| Merge #3: Add multiply to math.js | 2 | /** Returns the sum of a and b. */ |
| Add math helpers, tests and checks | 3 | function add(a, b) { |
| 4 | return a + b; | |
| 5 | } | |
| 6 | ||
| Merge #3: Add multiply to math.js | 7 | /** Returns the product of a and b. */ |
| 8 | function multiply(a, b) { | |
| 9 | return a * b; | |
| 10 | } | |
| 11 | ||
| Add mod function to math.js | 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 | ||
| Catch up with main | 20 | /** Returns base raised to the whole-number exponent; throws a RangeError if exponent is negative. */ |
| 21 | function power(base, exponent) { | |
| 22 | if (exponent < 0) { | |
| 23 | throw new RangeError("exponent must not be negative"); | |
| 24 | } | |
| 25 | let result = 1; | |
| 26 | for (let i = 0; i < exponent; i++) { | |
| 27 | result *= base; | |
| 28 | } | |
| 29 | return result; | |
| 30 | } | |
| 31 | ||
| Catch up with main | 32 | /** Returns the average of numbers; throws a TypeError if the array is empty. */ |
| 33 | function mean(numbers) { | |
| 34 | if (numbers.length === 0) { | |
| 35 | throw new TypeError("numbers must not be empty"); | |
| 36 | } | |
| 37 | return numbers.reduce((sum, n) => sum + n, 0) / numbers.length; | |
| 38 | } | |
| 39 | ||
| 40 | /** 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. */ | |
| 41 | function median(numbers) { | |
| 42 | if (numbers.length === 0) { | |
| 43 | throw new TypeError("numbers must not be empty"); | |
| 44 | } | |
| 45 | const sorted = [...numbers].sort((a, b) => a - b); | |
| 46 | const mid = Math.floor(sorted.length / 2); | |
| 47 | return sorted.length % 2 === 0 ? (sorted[mid - 1] + sorted[mid]) / 2 : sorted[mid]; | |
| 48 | } | |
| 49 | ||
| 50 | /** Returns the population standard deviation of numbers; throws a TypeError if the array is empty. */ | |
| 51 | function standard_deviation(numbers) { | |
| 52 | const avg = mean(numbers); | |
| 53 | const variance = numbers.reduce((sum, n) => sum + (n - avg) ** 2, 0) / numbers.length; | |
| 54 | return Math.sqrt(variance); | |
| 55 | } | |
| 56 | ||
| 57 | module.exports = { add, multiply, mod, power, mean, median, standard_deviation }; |
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