### Question:
VectorMath { public static double cosineSimilarity(float[] x, float[] y, double normY) { int length = x.length; double dot = 0.0; double totalXSq = 0.0; for (int i = 0; i < length; i++) { double xi = x[i]; totalXSq += xi * xi; dot += xi * y[i]; } return dot / (Math.sqrt(totalXSq) * normY); } private  VectorMath(); static double dot(float[] x, float[] y); static double norm(float[] x); static double norm(double[] x); static double cosineSimilarity(float[] x, float[] y, double normY); static double[] transposeTimesSelf(Collection<float[]> M); static double[] parseVector(String[] values); static float[] randomVectorF(int features, RandomGenerator random);  }### Answer:
@Test public void testCosineSimilarity() { assertEquals(0.13572757431921362, VectorMath.cosineSimilarity(VEC1, VEC2, VectorMath.norm(VEC2))); assertEquals(1.0, VectorMath.cosineSimilarity(VEC1, VEC1, VectorMath.norm(VEC1))); float[] bigVec = new float[1000]; Arrays.fill(bigVec, 3.1415926535e20f); float[] smallVec = new float[1000]; Arrays.fill(smallVec, -3.1415926535e-20f); assertEquals(-1.0, VectorMath.cosineSimilarity(bigVec, smallVec, VectorMath.norm(smallVec))); }