adding doctest

Author: MRJPEREZR

neural_network/backpropagation_weight_decay.py

@@ -113,13 +113,19 @@ def sigmoid(input_: float) -> float:
     """
     Sigmoid activation function
     Output layer
+    >>> sigmoid(0)
+    0.5
+    >>> round(sigmoid(1), 6)  # Approximation for 6 decimal places
+    0.731059
     """
     return 1 / (1 + np.exp(-input_))
 
 
 def d_sigmoid(input_: float) -> float:
     """
     Sigmoid activation derivate
+    >>> round(d_sigmoid(0), 6)
+    0.25
     """
     return sigmoid(input_) ** 2 * np.exp(-input_)