feat: add arithmetic and geometric mean calculation functions

maths/arithmetic_geometric_mean.ts

@@ -0,0 +1,59 @@
+/**
+ * @function calculateArithmeticMean
+ * @description Calculate the arithmetic mean of a list of numbers. Arithmetic mean is the sum of all the values divided by the number of values in the list. Valid for both positive and negative numbers.
+ * @param {number[]} values - Array of numeric values
+ * @returns {number} - arithmetic mean of input values
+ * @throws {TypeError} - If the input is not an array
+ * @throws {RangeError} - If the input array is empty
+ * @see https://en.wikipedia.org/wiki/Arithmetic_mean
+ * @example calculateArithmeticMean([1, 2, 4, 5]) = 3
+ */
+
+export const calculateArithmeticMean = (values: number[]) => {
+  // Check if the input is an array
+  if (Array.isArray(values) === false) {
+    throw new TypeError('Invalid Input')
+  }
+
+  // Check if the array is empty
+  if (values.length === 0) {
+    throw new RangeError('Input array cannot be empty')
+  }
+
+  // Calculate the arithmetic mean
+  const arithmeticMean =
+    values.reduce((sum, current) => sum + current, 0) / values.length
+
+  return arithmeticMean
+}
+
+/**
+ * @function calculateGeometricMean
+ * @description Calculate the geometric mean of list of numbers. It is the nth root of the product of n numbers. It is only valid for positive numbers.
+ * @param {number[]} values - Array of numeric values
+ * @returns {number} - geometric mean of input values
+ * @throws {TypeError} - If the input is not an array
+ * @throws {RangeError} - If the input array is empty
+ * @see https://en.wikipedia.org/wiki/Geometric_mean
+ * @example calculateGeometricMean([1, 2, 4, 5]) = 2.514866859365871
+ */
+
+export const calculateGeometricMean = (values: number[]) => {
+  //check if input is an array
+  if (Array.isArray(values) === false) {
+    throw new TypeError('Invalid Input')
+  }
+
+  //check if the array is empty
+  if (values.length === 0) {
+    throw new RangeError('Input array cannot be empty')
+  }
+
+  //calculate the geometric mean
+  const geometricMean = Math.pow(
+    values.reduce((product, current) => product * current, 1),
+    1 / values.length
+  )
+
+  return geometricMean
+}

maths/test/arithmetic_geometric_mean.test.ts

@@ -0,0 +1,36 @@
+import {
+  calculateArithmeticMean,
+  calculateGeometricMean
+} from '../arithmetic_geometric_mean'
+
+describe('Arithmetic Mean', () => {
+  test('Should return the arithmetic mean of list of numbers', () => {
+    expect(calculateArithmeticMean([1, 2, 3, 4])).toBe(2.5)
+  })
+
+  test('Should throw a TypeError if the input is not an array', () => {
+    expect(() => calculateArithmeticMean(1 as unknown as number[])).toThrow(
+      TypeError
+    )
+  })
+
+  test('Should throw a RangeError if the input array is empty', () => {
+    expect(() => calculateArithmeticMean([])).toThrow(RangeError)
+  })
+})
+
+describe('Geometric Mean', () => {
+  test('Should return geometric mean of list of numbers', () => {
+    expect(calculateGeometricMean([1, 2, 3, 4])).toBe(2.2133638394006434)
+  })
+
+  test('Should throw a TypeError if the input is not an array', () => {
+    expect(() => calculateGeometricMean(1 as unknown as number[])).toThrow(
+      TypeError
+    )
+  })
+
+  test('Shoud throw a RangeError if the input array is empty', () => {
+    expect(() => calculateGeometricMean([])).toThrow(RangeError)
+  })
+})