UGC NET CSE | November 2017 | Part 3 | Question: 72

Question

The Sigmoid activation function $f(t)$ is defined as

• A. $\dfrac{1}{\text{exp} (t) + \text{exp} (-t)}$
• B. $t \text{  exp}(-t)$
• C. $\dfrac{1}{1+ \text{exp} (t)}$
• D. $\dfrac{1}{1+ \text{exp} (-t)}$

Answer 1

Sigmoid functions are used in artificial neural networks to introduce nonlinearity in the model.

Correct option is (d)

Ref: https://excel.ucf.edu/classes/2007/Spring/appsII/Chapter1.pdf

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Answer 2

A sigmoid function is a mathematical function having a characteristic "S"-shaped curve or sigmoid curve. A common example of a sigmoid function is the logistic function shown in the first figure and defined by the formula:

(Source- wiki)

Hence, Option D is correct.