feat: determinant

HarryGogonis · Jun 25, 2017 · 01a7615 · 01a7615
1 parent c18f6e2
commit 01a7615
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Showing 2 changed files with 13 additions and 0 deletions.
diff --git a/src/index.js b/src/index.js
@@ -147,6 +147,13 @@ class Matrix extends Map {
     ]
     return `matrix(${values.join()})`
   }
+
+  /**
+   * @return {number} determinant of the current matrix
+   */
+  determinant () {
+    return (this.get('a') * this.get('d')) - (this.get('b') * this.get('c'))
+  }
 }
 
 export default Matrix
diff --git a/src/index.spec.js b/src/index.spec.js
@@ -110,3 +110,9 @@ describe('toString', () => {
     expect(str).toBe('matrix(6,5,4,3,2,1)')
   })
 })
+
+describe('determinant', () => {
+  expect(mockMatrix.determinant()).toBe(-2)
+  expect(new Matrix().determinant()).toBe(1)
+  expect(new Matrix(1, 1, 1, 1, 0, 0).determinant()).toBe(0)
+})