diff --git a/maths/sigmoid.py b/maths/sigmoid.py new file mode 100644 index 000000000..147588e88 --- /dev/null +++ b/maths/sigmoid.py @@ -0,0 +1,39 @@ +""" +This script demonstrates the implementation of the Sigmoid function. + +The function takes a vector of K real numbers as input and then 1 / (1 + exp(-x)). +After through Sigmoid, the element of the vector mostly 0 between 1. or 1 between -1. + +Script inspired from its corresponding Wikipedia article +https://en.wikipedia.org/wiki/Sigmoid_function +""" + +import numpy as np + + +def sigmoid(vector: np.array) -> np.array: + """ + Implements the sigmoid function + + Parameters: + vector (np.array): A numpy array of shape (1,n) + consisting of real values + + Returns: + sigmoid_vec (np.array): The input numpy array, after applying + sigmoid. + + Examples: + >>> sigmoid(np.array([-1.0, 1.0, 2.0])) + array([0.26894142, 0.73105858, 0.88079708]) + + >>> sigmoid(np.array([0.0])) + array([0.5]) + """ + return 1 / (1 + np.exp(-vector)) + + +if __name__ == "__main__": + import doctest + + doctest.testmod()