   }
 
   func testNormalize() {
-    let v1 = vec2(100, 1000)
+    let v1 = vec2(100.0, 1000.0)
     let v2 = v1.normalize()
     XCTAssertEqualWithAccuracy(v2.length, 1.0, accuracy: epsilon)
     XCTAssertEqualWithAccuracy(v1.angle, v2.angle, accuracy: epsilon)
   }
 
   func testNormalizeZero() {
-    let v1 = vec2(0, 0)
+    let v1 = vec2(0.0, 0.0)
     let v2 = v1.normalize()
     XCTAssertEqualWithAccuracy(v2.length, 0.0, accuracy: epsilon)
     XCTAssertEqualWithAccuracy(v1.angle, v2.angle, accuracy: epsilon)

    let p2 = CGPoint(x: 3, y: 4)

    let v1 = vec2(from:p1, to:p2)
    let v2 = vec2(2, 3)

    XCTAssertEqual(v1, v2)
  }

  }

  func testScale() {
    let v1 = vec2(4.0, 5.0)
    let l1 = v1.length

    let v2 = v1.scale(3.0)
