From 0ed8578dedcf415f8142bfe144597a6e7218070e Mon Sep 17 00:00:00 2001
From: Frederique Mittelstaedt <frederique@automorph.com>
Date: Thu, 7 Mar 2019 14:07:11 +0000
Subject: [PATCH] feat(calculator.ts): add inverse method

---
 src/Calculator.ts        | 5 +++++
 tests/Calculator.test.ts | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/src/Calculator.ts b/src/Calculator.ts
index 3c0eb36..0044d72 100644
--- a/src/Calculator.ts
+++ b/src/Calculator.ts
@@ -71,4 +71,9 @@ export default class Calculator {
     this.current = Math.tan(this.current);
     return this;
   }
+
+  public inverse() {
+    this.current = div(1, this.current);
+    return this;
+  }
 }
diff --git a/tests/Calculator.test.ts b/tests/Calculator.test.ts
index 3ad80e3..aa5a1c3 100644
--- a/tests/Calculator.test.ts
+++ b/tests/Calculator.test.ts
@@ -22,4 +22,6 @@ describe("Calculator", () => {
   it("can cos", () => expect(calculator.cos().value()).equal(1));
   // prettier-ignore
   it("can tan", () => expect(calculator.clear().tan().value()).equal(0));
+  // prettier-ignore
+  it("can invert", () => expect(calculator.clear().add(2).inverse().value()).equal(1 / 2));
 });