### Question:
Sigmoid extends TransferFunction implements Serializable { @Override public double getDerivative(double net) { double derivative = this.slope * this.output * (1d - this.output); return derivative; } Sigmoid();  Sigmoid(double slope);  Sigmoid(NeurophProperties properties); double getSlope(); void setSlope(double slope); @Override double getOutput(double netInput); @Override double getDerivative(double net);  }### Answer:
@Test public void testGetDerivative() { instance.getOutput(input); double result = instance.getDerivative(input); assertEquals(expected_derivative, result, FloatingAccuracy.ACCURACY); }