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