Sigmoid units, Computer Engineering

Sigmoid units:

Always remember that the function inside units take as input the weighted sum, S and of the values coming from the units connected to it. However the function inside sigmoid units calculates the following value that given a real-valued input S: is as

2248_Sigmoid units.png

Whereas e is the base of natural logarithms, e = 2.718... 

Where we plot the output from sigmoid units given various weighted sums as input that looks remarkably like a step function as: 

983_Sigmoid units1.png

Obviously by getting a differentiable function that looks like the step function was the whole point of the exercise. Moreover, not only is this function differentiable but  there the derivative is fairly simply expressed in terms of the function itself as: 

970_Sigmoid units2.png

So note that the output values for the σ function range between but never make it to 0 and 1. It means that e-S is never negative so the denominator of the fraction tends to 0 as S gets very big in the negative direction and then tends to 1 as it gets very big in the positive direction. In fact this tendency happens fairly quickly as: in the middle ground between 0 and 1 is rarely seen means the sharp or near step in the function. Just because of it looking like a step function that we can think of it firing and not-firing as in a perceptron as: if a positive real is input and the output will generally be close to +1 then a negative real is input the output will generally be close to -1.

Posted Date: 1/11/2013 7:11:17 AM | Location : United States







Related Discussions:- Sigmoid units, Assignment Help, Ask Question on Sigmoid units, Get Answer, Expert's Help, Sigmoid units Discussions

Write discussion on Sigmoid units
Your posts are moderated
Related Questions
In a positive logic system, logic state 1 corresponds to ? Ans. For positive digital logic, we choose two voltages levels. Higher voltage shows logic 1 and a lower voltage sho

Q. How to input to circuit? Register A bits as a0, a1, a2 and a3 in the corresponding X bits of the Full Adder (FA). Register B bits as given in the Figure above as in

State the Tips of timescale directive Include a `timescale directive at the top of each module, even if there are no delays i n the module, since some simulators may require th


What are the disadvantages of Public Key Cryptography? Disadvantages of Public Key Cryptography are as given below: a) It is used to encrypt a secret key that is used to e

Granularity Granularity refers to the quantity of computation done in concurrent relative to the size of whole program. In concurrent computing, granularity is a qualitative me

COMMUNICATIONS TECHNOLOGY: The development of communications technology is, in a sense, a symbol of man's effort to communicate rapidly over great distances. Communications te

Q. Number used as operand data type? Numbers: All machine languages comprise numeric data types. Numeric data generally use one of the three representations: o Floating po

Define Programmable Logic array & Programmable Array Logic? Combinational ckt is implemented with ROM Do not care conditions become an address input. PLA is alike to ROM. PLA d

Propositional Inference Rules -Artificial intelligence : Equivalence rules are specifically useful because of the vice-versa aspect,that means we can discover forwards andbackw