From dc4e89805a642d1c6e3fe031276edbfde3c1f40c Mon Sep 17 00:00:00 2001
From: Suyash Dongre <109069262+Suyashd999@users.noreply.github.com>
Date: Mon, 23 Oct 2023 10:57:33 +0530
Subject: [PATCH] Added docstring/documentation for sigmoid_function (#10756)

* Added doctest for sigmoid_function

* Added doctest for sigmoid_function

* Added doctest for sigmoid_function
---
 machine_learning/logistic_regression.py | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/machine_learning/logistic_regression.py b/machine_learning/logistic_regression.py
index 87bc8f668..f9da0104a 100644
--- a/machine_learning/logistic_regression.py
+++ b/machine_learning/logistic_regression.py
@@ -28,6 +28,21 @@ from sklearn import datasets
 
 
 def sigmoid_function(z):
+    """
+    Also known as Logistic Function.
+
+                1
+    f(x) =   -------
+              1 + e⁻ˣ
+
+    The sigmoid function approaches a value of 1 as its input 'x' becomes
+    increasing positive. Opposite for negative values.
+
+    Reference: https://en.wikipedia.org/wiki/Sigmoid_function
+
+    @param z:  input to the function
+    @returns: returns value in the range 0 to 1
+    """
     return 1 / (1 + np.exp(-z))