### Question:
Tanh extends TransferFunction implements Serializable { @Override final public double getDerivative(double input) { if (Math.abs(input) * slope > 100) { return 0.0d; } double E_x = Math.exp(2 * slope * input); double tanhsx = (E_x - 1d) / (E_x + 1d); derivativeOutput = amplitude * slope * (1.0d - tanhsx * tanhsx); return derivativeOutput; } Tanh();  Tanh(double slope);  Tanh(NeurophProperties properties); @Override final double getOutput(double input); @Override final double getDerivative(double input); double getSlope(); void setSlope(double slope); double getAmplitude(); void setAmplitude(double amplitude);  }### Answer:
@Test public void testGetDerivative() { double result = instance.getDerivative(input); assertEquals(expected_derivative, result, FloatingAccuracy.ACCURACY); }