Add ComplexNumber.

src/algorithms/math/complex-number/ComplexNumber.js

@@ -0,0 +1,73 @@
+export default class ComplexNumber {
+  /**
+   * @param {number} [real]
+   * @param {number} [imaginary]
+   */
+  constructor({ real = 0, imaginary = 0 } = {}) {
+    this.real = real;
+    this.imaginary = imaginary;
+  }
+
+  /**
+   * @param {ComplexNumber} addend
+   * @return {ComplexNumber}
+   */
+  add(addend) {
+    return new ComplexNumber({
+      real: this.real + addend.real,
+      imaginary: this.imaginary + addend.imaginary,
+    });
+  }
+
+  /**
+   * @param {ComplexNumber} subtrahend
+   * @return {ComplexNumber}
+   */
+  subtract(subtrahend) {
+    return new ComplexNumber({
+      real: this.real - subtrahend.real,
+      imaginary: this.imaginary - subtrahend.imaginary,
+    });
+  }
+
+  /**
+   * @param {ComplexNumber} multiplicand
+   * @return {ComplexNumber}
+   */
+  multiply(multiplicand) {
+    return new ComplexNumber({
+      real: this.real * multiplicand.real - this.imaginary * multiplicand.imaginary,
+      imaginary: this.real * multiplicand.imaginary + this.imaginary * multiplicand.real,
+    });
+  }
+
+  /**
+   * @param {ComplexNumber} divider
+   * @return {ComplexNumber}
+   */
+  divide(divider) {
+    // Get divider conjugate.
+    const dividerConjugate = this.conjugate(divider);
+
+    // Multiply dividend by divider's conjugate.
+    const finalDivident = this.multiply(dividerConjugate);
+
+    // Calculating final divider using formula (a + bi)(a − bi) = a^2 + b^2
+    const finalDivider = (divider.real ** 2) + (divider.imaginary ** 2);
+
+    return new ComplexNumber({
+      real: finalDivident.real / finalDivider,
+      imaginary: finalDivident.imaginary / finalDivider,
+    });
+  }
+
+  /**
+   * @param {ComplexNumber} complexNumber
+   */
+  conjugate(complexNumber) {
+    return new ComplexNumber({
+      real: complexNumber.real,
+      imaginary: -1 * complexNumber.imaginary,
+    });
+  }
+}