@Test public void testWeightedAndStdDev() { WeightedRunningAverageAndStdDev runningAverage = new WeightedRunningAverageAndStdDev(); assertEquals(0, runningAverage.getCount()); assertTrue(Double.isNaN(runningAverage.getAverage())); assertTrue(Double.isNaN(runningAverage.getStandardDeviation())); runningAverage.addDatum(1.0); assertEquals(1.0, runningAverage.getAverage(), EPSILON); assertTrue(Double.isNaN(runningAverage.getStandardDeviation())); runningAverage.addDatum(1.0, 2.0); assertEquals(1.0, runningAverage.getAverage(), EPSILON); assertEquals(0.0, runningAverage.getStandardDeviation(), EPSILON); runningAverage.addDatum(8.0, 0.5); assertEquals(2.0, runningAverage.getAverage(), EPSILON); assertEquals(Math.sqrt(10.5), runningAverage.getStandardDeviation(), EPSILON); runningAverage.addDatum(-4.0); assertEquals(2.0/3.0, runningAverage.getAverage(), EPSILON); assertEquals(Math.sqrt(15.75), runningAverage.getStandardDeviation(), EPSILON); runningAverage.removeDatum(-4.0); assertEquals(2.0, runningAverage.getAverage(), EPSILON); assertEquals(Math.sqrt(10.5), runningAverage.getStandardDeviation(), EPSILON); runningAverage.removeDatum(2.0, 2.0); assertEquals(2.0, runningAverage.getAverage(), EPSILON); assertEquals(Math.sqrt(31.5), runningAverage.getStandardDeviation(), EPSILON); }