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44 lines
1.1 KiB
Python
44 lines
1.1 KiB
Python
"""
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This script demonstrates the implementation of the tangent hyperbolic
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or tanh function.
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The function takes a vector of K real numbers as input and
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then (e^x - e^(-x))/(e^x + e^(-x)). After through tanh, the
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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 as np
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def tangent_hyperbolic(vector: np.ndarray) -> np.ndarray:
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"""
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Implements the tanh function
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Parameters:
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vector: np.ndarray
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Returns:
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tanh (np.array): The input numpy array after applying 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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>>> tangent_hyperbolic(np.array([1,5,6,-0.67]))
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array([ 0.76159416, 0.9999092 , 0.99998771, -0.58497988])
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>>> tangent_hyperbolic(np.array([8,10,2,-0.98,13]))
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array([ 0.99999977, 1. , 0.96402758, -0.7530659 , 1. ])
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"""
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return (2 / (1 + np.exp(-2 * vector))) - 1
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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