diff --git a/kotlin/complex-numbers/README.md b/kotlin/complex-numbers/README.md
new file mode 100644
index 0000000..950f8f0
--- /dev/null
+++ b/kotlin/complex-numbers/README.md
@@ -0,0 +1,14 @@
+# Complex Numbers
+
+A complex number is a number in the form `a + b * i` where `a` and `b` are real and `i` satisfies `i^2 = -1`.
+
+Assume the programming language you are using does not have an implementation of complex numbers.
+
+
+
+## Source
+
+Wikipedia [https://en.wikipedia.org/wiki/Complex_number](https://en.wikipedia.org/wiki/Complex_number)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.
diff --git a/kotlin/complex-numbers/build.gradle b/kotlin/complex-numbers/build.gradle
new file mode 100644
index 0000000..16c36c0
--- /dev/null
+++ b/kotlin/complex-numbers/build.gradle
@@ -0,0 +1,28 @@
+buildscript {
+ ext.kotlin_version = '1.1.1'
+ repositories {
+ mavenCentral()
+ }
+ dependencies {
+ classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+ }
+}
+
+apply plugin: 'kotlin'
+
+repositories {
+ mavenCentral()
+}
+
+dependencies {
+ compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+
+ testCompile 'junit:junit:4.12'
+ testCompile "org.jetbrains.kotlin:kotlin-test-junit:$kotlin_version"
+}
+test {
+ testLogging {
+ exceptionFormat = 'full'
+ events = ["passed", "failed", "skipped"]
+ }
+}
diff --git a/kotlin/complex-numbers/complex-numbers.iml b/kotlin/complex-numbers/complex-numbers.iml
new file mode 100644
index 0000000..e6e1008
--- /dev/null
+++ b/kotlin/complex-numbers/complex-numbers.iml
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module external.linked.project.id="complex-numbers" external.linked.project.path="$MODULE_DIR$" external.root.project.path="$MODULE_DIR$" external.system.id="GRADLE" external.system.module.group="" external.system.module.version="unspecified" type="JAVA_MODULE" version="4">
+ <component name="NewModuleRootManager" inherit-compiler-output="true">
+ <exclude-output />
+ <content url="file://$MODULE_DIR$">
+ <excludeFolder url="file://$MODULE_DIR$/.gradle" />
+ <excludeFolder url="file://$MODULE_DIR$/build" />
+ <excludeFolder url="file://$MODULE_DIR$/out" />
+ </content>
+ <orderEntry type="inheritedJdk" />
+ <orderEntry type="sourceFolder" forTests="false" />
+ </component>
+</module>
\ No newline at end of file
diff --git a/kotlin/complex-numbers/src/main/kotlin/ComplexNumber.kt b/kotlin/complex-numbers/src/main/kotlin/ComplexNumber.kt
new file mode 100644
index 0000000..c16aa51
--- /dev/null
+++ b/kotlin/complex-numbers/src/main/kotlin/ComplexNumber.kt
@@ -0,0 +1,53 @@
+data class ComplexNumber(val real: Double = 0.0, val imag: Double = 0.0){
+ operator fun plus(other: ComplexNumber): ComplexNumber{
+ return ComplexNumber(real = this.real + other.real, imag = this.imag + other.imag)
+ }
+
+ operator fun times(other: ComplexNumber): ComplexNumber{
+ val a = this.real
+ val b = this.imag
+ val c = other.real
+ val d = other.imag
+
+ return ComplexNumber(a*c - b*d, b*c + a * d)
+ }
+
+ operator fun minus(other: ComplexNumber): ComplexNumber{
+ return ComplexNumber(real = this.real - other.real, imag = this.imag - other.imag)
+ }
+
+ operator fun div(other: ComplexNumber): ComplexNumber{
+ val a = this.real
+ val b = this.imag
+ val c = other.real
+ val d = other.imag
+
+ return ComplexNumber(real = (a * c + b * d)/(c * c + d * d), imag = (b * c - a * d)/(c * c + d * d))
+ }
+
+ val abs: Double = Math.sqrt((real * real) + (imag * imag))
+ fun conjugate(): ComplexNumber {
+ return ComplexNumber(real = this.real, imag = this.imag.unaryMinus())
+ }
+
+ fun cos(): ComplexNumber{
+ val x = this.real
+ val y = this.imag
+ return ComplexNumber(Math.cos(x) * Math.cosh(y), (Math.sin(x) * Math.sinh(y)).unaryMinus())
+ }
+
+ fun sin(): ComplexNumber{
+ val x = this.real
+ val y = this.imag
+ return ComplexNumber(Math.sin(x) * Math.cosh(y), (Math.cos(x) * Math.sinh(y)))
+ }
+}
+
+// This implementation is silly, there is no documentation for it
+fun exponential(num: ComplexNumber): ComplexNumber{
+ val x = num.real
+ val y = num.imag
+
+
+ return ComplexNumber(real = Math.pow(Math.E, x), imag = 1.0) * ComplexNumber(real = 1.0, imag = Math.pow(Math.E, y))
+}
\ No newline at end of file
diff --git a/kotlin/complex-numbers/src/test/kotlin/ComplexNumberTest.kt b/kotlin/complex-numbers/src/test/kotlin/ComplexNumberTest.kt
new file mode 100644
index 0000000..0a554d8
--- /dev/null
+++ b/kotlin/complex-numbers/src/test/kotlin/ComplexNumberTest.kt
@@ -0,0 +1,266 @@
+import org.junit.Assert.assertEquals
+import org.junit.Ignore
+import org.junit.Test
+
+/*
+ * version: 1.0.0
+ */
+class ComplexNumberTest {
+
+ // Test helpers
+
+ companion object {
+ private const val DOUBLE_EQUALITY_TOLERANCE = 1e-15
+ }
+
+ private fun assertDoublesEqual(d1: Double, d2: Double) {
+ assertEquals(d1, d2, DOUBLE_EQUALITY_TOLERANCE)
+ }
+
+ private fun assertComplexNumbersEqual(c1: ComplexNumber, c2: ComplexNumber) {
+ assertDoublesEqual(c1.real, c2.real)
+ assertDoublesEqual(c1.imag, c2.imag)
+ }
+
+ // Tests
+
+ @Test
+ fun testImaginaryUnitExhibitsDefiningProperty() {
+ val expected = ComplexNumber(real = -1.0)
+ val actual = ComplexNumber(imag = 1.0) * ComplexNumber(imag = 1.0)
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testAdditionWithPurelyRealNumbers() {
+ val expected = ComplexNumber(real = 3.0)
+ val actual = ComplexNumber(real = 1.0) + ComplexNumber(real = 2.0)
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testAdditionWithPurelyImaginaryNumbers() {
+ val expected = ComplexNumber(imag = 3.0)
+ val actual = ComplexNumber(imag = 1.0) + ComplexNumber(imag = 2.0)
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testAdditionWithRealAndImaginaryParts() {
+ val expected = ComplexNumber(real = 4.0, imag = 6.0)
+ val actual = ComplexNumber(real = 1.0, imag = 2.0) + ComplexNumber(real = 3.0, imag = 4.0)
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testSubtractionWithPurelyRealNumbers() {
+ val expected = ComplexNumber(real = -1.0, imag = 0.0)
+ val actual = ComplexNumber(real = 1.0, imag = 0.0) - ComplexNumber(real = 2.0, imag = 0.0)
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testSubtractionWithPurelyImaginaryNumbers() {
+ val expected = ComplexNumber(imag = -1.0)
+ val actual = ComplexNumber(imag = 1.0) - ComplexNumber(imag = 2.0)
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testSubtractionWithRealAndImaginaryParts() {
+ val expected = ComplexNumber(real = -2.0, imag = -2.0)
+ val actual = ComplexNumber(real = 1.0, imag = 2.0) - ComplexNumber(real = 3.0, imag = 4.0)
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testMultiplicationWithPurelyRealNumbers() {
+ val expected = ComplexNumber(real = 2.0)
+ val actual = ComplexNumber(real = 1.0) * ComplexNumber(real = 2.0)
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testMultiplicationWithPurelyImaginaryNumbers() {
+ val expected = ComplexNumber(real = -2.0)
+ val actual = ComplexNumber(imag = 1.0) * ComplexNumber(imag = 2.0)
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testMultiplicationWithRealAndImaginaryParts() {
+ val expected = ComplexNumber(real = -5.0, imag = 10.0)
+ val actual = ComplexNumber(real = 1.0, imag = 2.0) * ComplexNumber(real = 3.0, imag = 4.0)
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testDivisionWithPurelyRealNumbers() {
+ val expected = ComplexNumber(real = 0.5)
+ val actual = ComplexNumber(real = 1.0) / ComplexNumber(real = 2.0)
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testDivisionWithPurelyImaginaryNumbers() {
+ val expected = ComplexNumber(real = 0.5)
+ val actual = ComplexNumber(imag = 1.0) / ComplexNumber(imag = 2.0)
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testDivisionWithRealAndImaginaryParts() {
+ val expected = ComplexNumber(real = 0.44, imag = 0.08)
+ val actual = ComplexNumber(real = 1.0, imag = 2.0) / ComplexNumber(real = 3.0, imag = 4.0)
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testAbsoluteValueOfPositivePurelyRealNumber() {
+ val expected = 5.0
+ val actual = ComplexNumber(real = 5.0).abs
+ assertDoublesEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testAbsoluteValueOfNegativePurelyRealNumber() {
+ val expected = 5.0
+ val actual = ComplexNumber(real = -5.0).abs
+ assertDoublesEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testAbsoluteValueOfPurelyImaginaryNumberWithPositiveImaginaryPart() {
+ val expected = 5.0
+ val actual = ComplexNumber(imag = 5.0).abs
+ assertDoublesEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testAbsoluteValueOfPurelyImaginaryNumberWithNegativeImaginaryPart() {
+ val expected = 5.0
+ val actual = ComplexNumber(imag = -5.0).abs
+ assertDoublesEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testAbsoluteValueOfNumberWithRealAndImaginaryParts() {
+ val expected = 5.0
+ val actual = ComplexNumber(real = 3.0, imag = 4.0).abs
+ assertDoublesEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testConjugationOfPurelyRealNumber() {
+ val expected = ComplexNumber(real = 5.0)
+ val actual = ComplexNumber(real = 5.0).conjugate()
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testConjugationOfPurelyImaginaryNumber() {
+ val expected = ComplexNumber(imag = -5.0)
+ val actual = ComplexNumber(imag = 5.0).conjugate()
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testConjugationOfNumberWithRealAndImaginaryParts() {
+ val expected = ComplexNumber(real = 1.0, imag = -1.0)
+ val actual = ComplexNumber(real = 1.0, imag = 1.0).conjugate()
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testRealPartOfPurelyRealNumber() {
+ val expected = 1.0
+ val actual = ComplexNumber(real = 1.0).real
+ assertDoublesEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testRealPartOfPurelyImaginaryNumber() {
+ val expected = 0.0
+ val actual = ComplexNumber(imag = 1.0).real
+ assertDoublesEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testRealPartOfNumberWithRealAndImaginaryParts() {
+ val expected = 1.0
+ val actual = ComplexNumber(real = 1.0, imag = 2.0).real
+ assertDoublesEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testImaginaryPartOfPurelyRealNumber() {
+ val expected = 0.0
+ val actual = ComplexNumber(real = 1.0).imag
+ assertDoublesEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testImaginaryPartOfPurelyImaginaryNumber() {
+ val expected = 1.0
+ val actual = ComplexNumber(imag = 1.0).imag
+ assertDoublesEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testImaginaryPartOfNumberWithRealAndImaginaryParts() {
+ val expected = 2.0
+ val actual = ComplexNumber(real = 1.0, imag = 2.0).imag
+ assertDoublesEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testExponentialOfPurelyImaginaryNumber() {
+ val expected = ComplexNumber(real = -1.0)
+ val actual = exponential(ComplexNumber(imag = Math.PI))
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testExponentialOfZero() {
+ val expected = ComplexNumber(real = 1.0)
+ val actual = exponential(ComplexNumber())
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+ @Ignore
+ @Test
+ fun testExponentialOfPurelyRealNumber() {
+ val expected = ComplexNumber(real = Math.E)
+ val actual = exponential(ComplexNumber(real = 1.0))
+ assertComplexNumbersEqual(expected, actual)
+ }
+
+}