* the expected output from the sigmoid function
*/
private void testValue(final double input, final double expected) {
LOGGER.debug("===== Sigmoid Function Test. =====");
IActivationFunction f = new SigmoidFunction();
double v = f.activate(input);
LOGGER.debug(" Input: " + input);
LOGGER.debug(" Value: " + v);
LOGGER.debug(" Expected: " + expected);
assertEquals(v, expected , DELTA * Math.ulp(expected));
LOGGER.debug("==================================");