Apr 3, 2024 · Mar 7, 2024 · Mar 26, 2024
diff --git a/Maths/BisectionMethod.js b/Maths/BisectionMethod.js

  // Bolzano theorem
  const hasRoot = (a, b, func) => {
    return func(a) * func(b) < 0
    return func(a) * func(b) <= 0
  }
  if (hasRoot(a, b, func) === false) {
    throw Error(
  const prod2 = fm * func(b)

  // Depending on the sign of the products above, decide which position will m fill (a's or b's)
  if (prod1 > 0 && prod2 < 0) return findRoot(m, b, func, --numberOfIterations)
  else if (prod1 < 0 && prod2 > 0)
    return findRoot(a, m, func, --numberOfIterations)
  else throw Error('Unexpected behavior')
  if (prod2 <= 0) return findRoot(m, b, func, --numberOfIterations)

  return findRoot(a, m, func, --numberOfIterations)
 }

 export { findRoot }
diff --git a/Maths/test/BisectionMethod.test.js b/Maths/test/BisectionMethod.test.js
 import { findRoot } from '../BisectionMethod'

 test('Equation f(x) = x^2 - 3*x + 2 = 0, has root x = 1 in [a, b] = [0, 1.5]', () => {
  const root = findRoot(
    0,
    1.5,
    (x) => {
      return Math.pow(x, 2) - 3 * x + 2
    },
    8
  )
  const root = findRoot(0, 1.5, (x) => x ** 2 - 3 * x + 2, 8)
  expect(root).toBe(0.9990234375)
 })

  )
  expect(Number(Number(root).toPrecision(8))).toBe(0.93945851)
 })

 test('Equation f(x) = x^3 = 0, has root x = 0.0 in [a, b] = [-1.0, 1.0]', () => {
  const root = findRoot(-1.0, 1.0, (x) => x ** 3, 32)
  expect(root).toBeCloseTo(0.0, 5)
 })

 test('Throws an error when function does not change sign', () => {
  expect(() => findRoot(-1.0, 1.0, (x) => x ** 2, 10)).toThrowError()
 })
Original file line number	Diff line number	Diff line change
Expand Up		@@ -23,7 +23,7 @@ const findRoot = (a, b, func, numberOfIterations) => {

		// Bolzano theorem
		const hasRoot = (a, b, func) => {
		return func(a) * func(b) < 0
		return func(a) * func(b) <= 0
		}
		if (hasRoot(a, b, func) === false) {
		throw Error(
Expand All		@@ -45,10 +45,9 @@ const findRoot = (a, b, func, numberOfIterations) => {
		const prod2 = fm * func(b)

		// Depending on the sign of the products above, decide which position will m fill (a's or b's)
		if (prod1 > 0 && prod2 < 0) return findRoot(m, b, func, --numberOfIterations)
		else if (prod1 < 0 && prod2 > 0)
		return findRoot(a, m, func, --numberOfIterations)
		else throw Error('Unexpected behavior')
		if (prod2 <= 0) return findRoot(m, b, func, --numberOfIterations)

		return findRoot(a, m, func, --numberOfIterations)
		}

		export { findRoot }
Original file line number	Diff line number	Diff line change
		@@ -1,14 +1,7 @@
		import { findRoot } from '../BisectionMethod'

		test('Equation f(x) = x^2 - 3*x + 2 = 0, has root x = 1 in [a, b] = [0, 1.5]', () => {
		const root = findRoot(
		0,
		1.5,
		(x) => {
		return Math.pow(x, 2) - 3 * x + 2
		},
		8
		)
		const root = findRoot(0, 1.5, (x) => x ** 2 - 3 * x + 2, 8)
		expect(root).toBe(0.9990234375)
		})

Expand All		@@ -35,3 +28,12 @@ test('Equation f(x) = sqrt(x) + e^(2x) - 8x = 0, has root x = 0.93945851 in [a
		)
		expect(Number(Number(root).toPrecision(8))).toBe(0.93945851)
		})

		test('Equation f(x) = x^3 = 0, has root x = 0.0 in [a, b] = [-1.0, 1.0]', () => {
		const root = findRoot(-1.0, 1.0, (x) => x ** 3, 32)
		expect(root).toBeCloseTo(0.0, 5)
		})

		test('Throws an error when function does not change sign', () => {
		expect(() => findRoot(-1.0, 1.0, (x) => x ** 2, 10)).toThrowError()
		})