Added QuadraticRoots to Math/QuadraticRoots.js (TheAlgorithms#1376)

Dibya12345 · chapati456 · appgurueu · web-flow · commit f271a2cae01c · 2023-10-02T12:42:39.000+05:30
* Added QuadraticRoots in the Math/QuadraticRoots * Fixed math/QyadraticRoots var to let * Added relevant links math/QyadraticRoots * Added relevant links math/QyadraticRoots and fixed let - const * Added the changes and @see notation in Math/QuadraticRoots.js * Added the changes Math/QuadraticRoots.js and return an empty [] * Readd describe block, remove redundant comments * Changed [1,1] to [1] --------- Co-authored-by: Dibya <Dibya.DebayanDash@siriuscom.com> Co-authored-by: Lars Müller <34514239+appgurueu@users.noreply.github.com>
diff --git a/Maths/QuadraticRoots.js b/Maths/QuadraticRoots.js
@@ -0,0 +1,37 @@
+/**
+ * @see https://www.cuemath.com/algebra/roots-of-quadratic-equation/
+ * @author Dibya Debayan Dash
+ * Calculates the roots of a quadratic equation of the form ax^2 + bx + c = 0.
+ *
+ * @param {number} a - Coefficient of x^2.
+ * @param {number} b - Coefficient of x.
+ * @param {number} c - Constant term.
+ * @returns {number[]} - An array containing the roots if they are real,
+ *                      or an empty array indicating no real roots.
+ *
+ * @example
+ * // Find the roots of the quadratic equation: 2x^2 - 4x + 2 = 0
+ * const roots = quadraticRoots(2, -4, 2);
+ * // Expected output: [1]
+ */
+const quadraticRoots = (a, b, c) => {
+  // Calculate the discriminant
+  const discriminant = b * b - 4 * a * c
+
+  // Check if roots are real
+  if (discriminant < 0) {
+    return []
+  } else if (discriminant === 0) {
+    // One real root
+    return [-b / (2 * a)]
+  } else {
+    // Two real roots
+    const sqrtDiscriminant = Math.sqrt(discriminant)
+    return [
+      (-b + sqrtDiscriminant) / (2 * a),
+      (-b - sqrtDiscriminant) / (2 * a)
+    ]
+  }
+}
+
+export { quadraticRoots }
diff --git a/Maths/test/QuadraticRoots.test.js b/Maths/test/QuadraticRoots.test.js
@@ -0,0 +1,13 @@
+import { quadraticRoots } from '../QuadraticRoots.js'
+
+describe('quadratic roots', () => {
+  it('returns an array with two real roots when the discriminant is positive', () => {
+    expect(quadraticRoots(1, -3, 2)).toEqual([2, 1])
+  })
+  it('returns an array with one real root when the discriminant is zero', () => {
+    expect(quadraticRoots(1, -2, 1)).toEqual([1])
+  })
+  it('returns an empty array indicating no real roots when the discriminant is negative', () => {
+    expect(quadraticRoots(1, 2, 5)).toEqual([])
+  })
+})
