""" This script demonstrates the implementation of the tangent hyperbolic or tanh function. The function takes a vector of K real numbers as input and then (e^x - e^(-x))/(e^x + e^(-x)). After through tanh, the element of the vector mostly -1 between 1. Script inspired from its corresponding Wikipedia article https://en.wikipedia.org/wiki/Activation_function """ import numpy import numpy as np import doctest def tanh_func(vector: np.array) -> np.array: """ Implements the tanh function Parameters: vector: np.array Returns: tanh (np.array): The input numpy array after applying tanh. mathematically (e^x - e^(-x))/(e^x + e^(-x)) can be written as (2/(1+e^(-2x))-1 Examples: >>> tanh_func(np.array([1, 5, 6, 113, 13, 16, -5.23])) array([ 0.76159416, 0.9999092 , 0.99998771, 1. , 1. , 1. , -0.99994268]) """ exp_vector = np.exp(-2 * vector) return (2 / (1 + exp_vector)) - 1 if __name__ == '__main__': doctest.testmod()