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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Machine Learning - The Sigmoid Function
Calculate Node Output.
Task
You are given the values for w1, w2, b, x1 and x2 and you must compute the output for the node. Use the sigmoid as the activation function.
Input Format
w1, w2, b, x1 and x2 on one line separated by spaces
Output…
Mr. Zero
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Sigmoid function output
I have the following neural network model.
nn_classifier = Sequential()
nn_classifier.add(Dense(output_dim = 16 ,activation='relu',input_dim = 13))
nn_classifier.add(Dense(output_dim = 16,activation='relu'))
nn_classifier.add(Dense(output_dim = 1,…
user6771624
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Logistic regression Maximum Likelihood in rapidminer
I wanted to get the maximum likelihood in logistic regression with this result (I'm really not sure if this is how it looks like):
I am currently using logistic regression to National Achievement Test(a performance exam for students,NAT…
Nathalie Joy Galia
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1 answer
How to replace the softmax layer with sigmoid layer? (Theano, MNIST classification)
I need your help. I am trying to modify the python-based neural network for MNIST data classification developed by M. Nielsen [http://neuralnetworksanddeeplearning.com/index.html].
Particularly, I am using networ3.py script. It employs Theano…
Arsen
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Writing the sigmoid function in octave and calculating sigmoid of 0 and negative numbers
I am a beginner to machine learning and octave. I am trying to write a code in octave that would calculate the sigmoid function g(z)=g(z)=1./(1+exp(-(z)));
When I try to find g(0) or g(-5) I get this error message:error: g(-5): subscripts must be…
Paulina Mensah
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1 answer
How does the output of the sigmoid function of two matrices multiplied look like?
Assuming I have the function sigmoid(W*x) where W is a 2x2 matrix and x is a 2x1 matrix. How would that output sigmoid(W*x) look like?
IHaveAQuestion
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If f(w) = log(sigmoid(w^T*x)) calculate the gradient (d/dw) of f(w)
w is an (nx1) vector and X is an (nxn) matrix. Here's my work:
However this site (http://www.matrixcalculus.org/) says that the derivative should be
What am I doing wrong?
AmmarMZ
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Why does my sigmoid function return values not in the interval ]0,1[?
I am implementing logistic regression in Python with numpy. I have generated the following data set:
# class 0:
# covariance matrix and mean
cov0 = np.array([[5,-4],[-4,4]])
mean0 = np.array([2.,3])
# number of data points
m0 = 1000
# class 1
#…
hispaniccoder
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Logistic Regression: math domain error - sigmoid function give value 1
I'm trying out logistic regression. While running the code, i get math domain error in python. Found out that i'm inputting (mx+b > 38) values large than 38 into the sigmoid function and it outputs 1, and the log function (-log(1-1)) spits out "math…
Deepak S.M
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2 answers
How to normalize data that goes from - inf to +inf between 0,1 where the value 0 is always equals to 0.5 when normalized?
I'm trying to normalize a dataset for a neural network, in the dataset are negatives and positives values that can go from -inf to +inf.
I need to normalize the negatives values between 0,0.5 and the positive values between 0.5,1 but the normalized…
William Silveira
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How can Activation function do its task?
I have a simple question. I know that the main purpose of activation function is to convert an input signal of a node to an output signal. And that output signal is gonna used as an input in the next layer. But I dont have any idea about the way…
Z Bokaee
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why sigmod function is used in logistics regression?
I did some search by google and got a few answers but they all have their own problems. For example
The result of sigmod will between 0 and 1.
This is good but sigmod function is not the only function whose result is between 0 and 1
It is…
Kramer Li
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Reverse sigmoid function in python
How can I create a reverse sigmoid function? I have created the following one but am not getting the desired output.
def sigmoid(x):
return - (1 / (1 + math.exp(0.5*x)))
x= np.linspace(0,5,100)
y = np.vectorize(sigmoid)
plt.plot(x,y(x))
Please…
AnonymousScientificUser
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The ouput of Dense(1,activation='sigmoid'), is it the probability y=1 or y=0 for binary classification problem?
I used the integer encoding for the classes 0 for first class and 1 for second.
So just wanted to know the output corresponds to which probability first class or second class?
Thanks a lot
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Is there a way to round very large fractions like 3.7625745528893614e-83?
I have a large number of type float (3.7625745528893614e-83) which must go through the sigmoid function:
def sigmoid_one(x):#sigmoid computation function
return (1/(1+math.e**(-x)))
,but after passing a large number (that is, a number with many…
viv3000
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