# Questions tagged [activation-function]

Activation function is a non-linear transformation, usually applied in neural networks to the output of the linear or convolutional layer. Common activation functions: sigmoid, tanh, ReLU, etc.

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### Word embedding autoencoder

I'm trying to train a word embedding autoencoder, but it either doesn't train, or trains but doesn't make predictions. I know I'm doing something wrong, so any help is greatly appreciated. Here is my ...
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### Relationship between Sigmoid and Gaussing Distribution

I was reading this article where I came across the following statement in the context of "Why do we use sigmoid activation function in Neural Nets?": The assumption of a dependent variable to follow ...
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### Bounded regression problem: sigmoid, hard sigmoid or…?

I have been training a neural network for a bounded regression and I am still in doubt for which activation function to use on the output layer. At first, I was convinced that a sigmoid would be the ...
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### Why activation function is not needed during the runtime of an Word2Vec model

In Word2Vec trainable model, there are two different weight matrix. The matrix $W$ from input-to-hidden layer and the matrix $W'$ from hidden-to-output layer. Referring to this article, I understand ...
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### Activation Function

I am very new to machine learning and made an experiment myself. I have a few questions: Can I use $Y = sin(x)$ or $Y = 2x$ as an activation function for a neural network? Is it necessary to increase ...
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### What are the best activation functions for Binary text classification in neural networks?

I know that there are many activation functions like Relu, sigmoid, tanh ..etc, I just want to know the best one for my case - Binary text classification. I have heard that Relu is best for Binary ...
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### How to Implement Biological Neuron Activations in Artificial Neural Networks

In artificial neural networks, activation functions are used for neurons, i.e. the sigmoid activation: Which can be implemented in code as (in Python): ...
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### How can the ReLU function lead to convergence?

The gradient descent algorithm is based on the fact that the gradient decreases as we move towards the optimum point. However, in the activations by the ReLU ...
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### Input and output layer activation functions of neurons in Orange

What are the activation functions of the neurons in the input and output layer of a neural network model from the Orange machine learning application?
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### Is it wrong to use Glorot Initialization with ReLu Activation?

I'm reading that keras' default initialization is glorot_uniform. However, all of the tutorials I see are using relu ...
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### If the input to the autoencoder is normalized, do we need to use sigmoid on the last layer?

According to: https://stackoverflow.com/questions/65307833/why-is-the-decoder-in-an-autoencoder-uses-a-sigmoid-on-the-last-layer The last layer activation function contains sigmoid in order to the ...
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### Is there comprehensive list of activation functions and their applications for a Neural Network?

I am aware of common activation functions like sigmoid, tanh,ReLu, Leaky ReLu. Even heard about a function called Swish. Now is there any detailed information on other activations functions and some ...
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### Is it possible to customize the activation function in scikit-learn's MLPRegressor?

Similar to this question about MLPClassifier, I suspect the answer is 'no' but I will ask it anyway. Is it possible to change the activation function of the output layer in an MLPRegressor neural ...
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### Can this dataset be separated linearly?

Is this dataset linearly separable? If not, can it be converted into one by applying some function as it seems to follow the same pattern? Also, which classification algorithms could be used to fit ...
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### Example of convex activation function

For a particular task, I need a convex activation function with the following properties: f''(x) > 0 0 <= f(x) <= 1 f(x) is monotonic f(x) is not "exploding" i.e. avoiding functions such as ...
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### Applying activation on part of the layer in Keras

Context I am trying to implement the YOLO algorithm in Keras. What I have so far is the following network: ...
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### Should output data scaling correspond to the activation function's output?

I am building an LSTM with keras which have an activation parameter in the layer. I have read that scaling on the output data ...
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### Why the gradient of a ReLU for X>0 is 1?

Gradient is derivative of several variables. I can't understand why is the gradient of a ReLU for X>0 is 1 ? and 0 for x < 0 ? I tried to search for proof and examples but didn't found any good ...
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### Is it possible to implement a vectorized version of a Maxout activation function?

I want to implement an efficient and vectorized Maxout activation function using python numpy. Here is the paper in which "Maxout Network" was introduced (by Goodfellow et al). For example, ...
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### Are non-relu activations better for small/ dense datasets?

Building on the questions below, the only conclusion I could draw from the answers was that ReLu is less computationally expensive and better at sparsity. Why is ...
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### Few activation functions handling various problems - neural networks

How can a few activation functions in neural networks handle so many different problems? I know some basics theory behind ANN, but I can't get what functions like the sigmoid function etc. have in ...
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### Training set Distribution and Activation function/Loss function correlation

How should the probability distribution of the training set influence the choice of the activation function / loss function? For instance if I have a Multinoulli distribution, which activation ...
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### Why leaky relu is not so common in real practice?

As leaky relu does not lead any value to 0, so training always continues. And I can't think of any disadvantages it have. Yet Leaky relu is less popular than Relu in real practice. Can someone tell ...
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### Do Activation Functions map to Higher Dimensions?:

I just started learning tensorflow and I have a question regarding activation functions used in neural networks, I watched a 3b1b video a while ago and it seems it squished the value into an interval ...
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### Numerically stable hyperbolic tangent

The hyperbolic tangent is commonly used as an activation function: $$tanh(x) = \frac{e^x - e^{-x}}{e^x + e^{-x}}$$ Although, it is unclear how this function is implemented to be numerically stable ...
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### Activation function vs Squashing function

This may seem like a very simple and obvious question, but I haven't actually been able to find a direct answer. Today, in a video explaining deep neural networks, I came across the term Squashing ...
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### Can there be in-active neuron in output layer

I am new to deep learning, and was studying about it. I know that input from input layer is multiplied with weights and then added with bias. And output of this is passed to a activation function of a ...
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### Why is ReLU used as an activation function?

Activation functions are used to introduce non-linearities in the linear output of the type w * x + b in a neural network. Which I am able to understand ...
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### What is GELU activation?

I was going through BERT paper which uses GELU (Gaussian Error Linear Unit) which states equation as $$GELU(x) = xP(X ≤ x) = xΦ(x).$$ which in turn is approximated to 0.5x(1 + tanh[\sqrt{ 2/π}(x + ...
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### Does the number of hidden layers affect the activation function?

Suppose there's a network with N hidden layers. There are 2 cases: The network is deep The network is shallow I've been wondering how ...
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### Guidelines to efficiently train neural networks which have polynomial activations

I am interesting in studying low footprint NN by replacing the activation functions with low-degree polynomial approximations. Doing this, I am fine with slight reduction in accuracy if I the training ...
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ReLU is used as an activation function that serves two purposes: Breaking linearity in DNN. Helping in handling Vanishing Gradient problem. For Exploding Gradient problem, we use Gradient Clipping ...
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### tanh function values are either 1 or -1, how to interpret that distribution

I have a question regarding the tanh function. I trained an NN (with tanh activation functions in hidden layers) on a multiclass dataset and visualised the tanh values of the complete samples from the ...
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### Deep Neural Network and Activation Function

I want to know why we need Activation function in DNN hidden layers. I know a bit, like it will help us in, Increasing model complexity and introduce non-linearity Avoiding Gradient Vanishing ...
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### Sigmoid vs Softmax with cross entropy

For a binary classifier, Is there any difference in Sigmoid activation function vs Softmax with cross entropy ? In this answer how-to-maximize-recall it is stated that if we use softmax with cross ...
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### How to use LeakyRelu as activation function in sequence DNN in keras?When it perfoms better than Relu?

How do you use LeakyRelu as an activation function in sequence DNN in keras? If I want to write something similar to: ...
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### Is it possible to get an ROC curve using Relu activation?

Based on my understanding, given that Relu doesn't provide probabilities unlike Softmax, it's not possible to plot an ROC curve. However, is there some way to convert the output from a Relu to ...
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### Sigmoid activation function for scaled continuous data

I've been working on a NLP project that attempt to output a single numeric value. The natural form of the data is integers between 0 and 27, with 27 being an absolute maximum, and values above 27 ...
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### Does sigmoid facilitate modeling non-linear decision boundaries or does this come from high-dimensional data?

I'm writing up a neural network using sigmoid as the activation function. According to one lecture, sigmoid simply squashes numbers onto the (0,1) interval. To model non-linear decision boundaries, ...
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### How to determine activation functions for neural network

I am trying to plan a neural network for regression predictions. The final activation layer should be a linear function, but for hidden layers, do the activation functions need to also be all linear ...
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### Can we talk about vanishing activations?

When updating the weights of a deep neural network using backpropagation, to update the weights of a given hidden layer, we use both the partial derivatives of the objective function with respect to ...
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### Scaling the activation function

It is obvious that I have to scale the output data if the range of values is between say [-10;10] and the activation function of the output layer takes values in the interval [-1;1]. But I could also ...
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### How to deal with ternary Output neurons in the Output classification layer of a simple feedforward Neural Net?

I was looking into the multi-label classification on the output layer of a Neural Network. I have 5 Output Neurons where each Neuron can be 1, 0, or -1. independent of other Neurons. So for example an ...
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### Why there is no exact picture of softmax activation function?

I was wondering why there is no precise picture of the softmax activation function on the internet. Is it difficult for the plot or what is the reason behind that since I want to compare it with a ...
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### Problem with convergence of ReLu in MLP

I created neural network from scratch in python using only numpy and I'm playing with different activation functions. What I observed is quite weird and I would love to understand why this happens. ...
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### Avoid saturation in activation function (sigmoid)

Background It is said Sigmoid/Tanh are not to use because of the saturation issue. Question The saturation occurs when the input to Sigmoid/Tanh is a large value. Will normalizing the input between -...
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### How does Pytorch deal with non-differentiable activation functions during backprop?

I've read many posts on how Pytorch deal with non-differentiability in the network due to non-differentiable (or almost everywhere differentiable - doesn't make it that much better) activation ...