A sigmoid function is a mathematical function having an "S" shape (sigmoid curve). Often, sigmoid function refers to the special case of the logistic function defined by the formula S ( t ) = 1 / (1 + e^-t)
Sigmoid function (Wikipedia)
Questions tagged [sigmoid]
256 questions
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1 answer
Teaching a fully connected feed-forward neural network XOR function
I'm trying to teach my multilayer neural network the XOR function. I have a network with architecture [2, 2, 1]. I define the loss as sum of square errors (I know it's not ideal, but I need it like that). If I set the activation function for all…
Zlatan Sičanica
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1 answer
Java Sigmoid method returns Incorrect Results
I wrote out a sigmoid function in java that works fine when dealing with single numbers but when given an array fails after the first data entry.
Here's some data to Illustrate my problem (with output rounded to 3 digits).
Input | Correct Output…
Fraser
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1 answer
sigmoid() or tanh() activation function in linear system with neural network
I am trying to build a Neural Network to study one problem with a continuous output variable. A schematic representation of the neural network used is described below
Schematic representation of neural network: input layer size = 1; hidden layer…
chayanquete
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1 answer
Simple non-linear boundary with sigmoid neuron for OR function
I would like to compute a non linear boundary with sigmoid neurons with an input layer and output layer. The neuron has 2 inputs x1, x2 and a bias. I am trying to compute this.
How is this done. For the perceptron if
w*x +b >= 0 for…
Tinniam V. Ganesh
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2 answers
Sigmoid always returns 1?
Consider the following:
def sigmoid(inSig):
return 1.0/(1.0+np.exp(-inSig))
def classifyVector(inX, weights):
prob = sigmoid(sum(inX*weights))
if prob > 0.5: return 1.0
else: return 0.0
My understanding is that the sigmoid result…
swabygw
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1 answer
Automatically finding starting values for a sigmoid curve
I have ~10.000 of vectors and I want to fit a sigmoid curve to each of them; in each case, I need to define starting parameters for fitting, so I want to find these parameters automatically. On stackexchange, there are discussed strategies of…
khorms
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Neural network for iris data set
Background: I'm writing in Python a three-layer neural network using mini-batch stochastic gradient descent specifically designed to identify between three classes of iris plants from the famous iris data set. The input layer has four neurons, one…
Victor Kwon
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1 answer
Deal with errors in parametrised sigmoid function in python
I am trying to convert a set of numbers into sigmoids:
actualarray = {
'open_cost_1':{
'cost_matrix': [
{'a': 24,'b': 56,'c': 78},
{'a': 3,'b': 98,'c':1711},
{'a': 121,'b': 12121,'c': 12989121},
…
Dhruv Ghulati
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sigmoid function in vb
Can anyone code a simple sigmoid function in vb.net? I have tried and I don't think it works. If anyone could suggest any improvements and/or fixes, I would be very happy. Thanks!
Function sigmoid(inputs As Single)
Dim finish As New…
Samuel Lopes
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- 7
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1 answer
neural net sigmoid function "takes exactly 1 argument (2 given)"
trying to forward propagate some data through a neural net
import numpy as np
import matplotlib.pyplot as plt
class Neural_Network(object):
def __init__(self):
#Define Hyperparameters
self.inputLayerSize = 2
self.outputLayerSize…
mleafer
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9 answers
Calculate the sigmoid function
I am learning about machine learning from coursera. I am trying to calculate the sigmoid function and i have the below code:
function g = sigmoid(z)
%SIGMOID Compute sigmoid functoon
% J = SIGMOID(z) computes the sigmoid of z.
% You need to…
user6658936
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votes
2 answers
estimate the slope of the straight part in boltzmann curve
I was working with one dataset and found the curve to be sigmoidal. i have fitted the curve and got the equation A2+((A1-A2)/1+exp((x-x0)/dx)) where:
x0 : Mid point of the curve
dx : slope of the curve
I need to find the slope and midpoint in…
pkt
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- 12
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0 answers
How to make python add small numbers accurately
I am running some experiments which require use of the following function:
import math
def sigmoid(x):
return 1.0 / (1.0 + math.exp(-x))
The function returns a number from 0.0 to 1.0 (see https://en.wikipedia.org/wiki/Sigmoid_function). If I…
Siato
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1 answer
Delta component doesnt show in weight learning rule of sigmoid activation MLP
As a basic proof of concept, in a network that classifies K classes with input x, bias b, output y,S samples, weights v and t teacher signal in which t(k) equals 1 if the matching sample is under k class.
Variables
Let x_(is) represent the i_(th)…
masarmor
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- 3
-1
votes
1 answer
How to start sigmoid from origin?
Desired graph
There are several different implementations of sigmoid function in Python, but all of them started from negative x coordinate axis. But how to start it from x=0?
