## nightly caffe2op-activation

xxx

### 3 releases

 0.1.5-alpha.0 Mar 25, 2023 Mar 3, 2023 Mar 2, 2023

Used in caffe2op-elu

BSD-3-Clause

1MB
6.5K SLoC

This rust crate provides mathematical operators for DSP and machine learning computations.

Note: This crate is currently being translated from C++ to Rust, and some function bodies may still be in the process of translation.

It includes operations for implementing activation functions commonly used in neural networks and other machine learning models. The crate provides functions for computing the forward and backward pass of these activation functions, such as cudnnActivationForward and cudnnActivationBackward.

The crate also provides functions for setting and modifying the activation function properties, such as the activation mode, which is defined by CudnnActivationMode and kCudnnActivationMode. The SetTensorDescriptor function is also included for setting up the input and output tensors.

The crate implements various activation functions, such as the sigmoid function, which is defined by the equation:

f(x) = 1 / (1 + e^(-x))

Another example is the ReLU function, which is defined as:

f(x) = max(0, x)

Overall, this rust crate is a useful tool for implementing and optimizing machine learning models that rely on activation functions, and for performing DSP computations in general.

3> would you please list for me as many activation functions as you can think of along with their mathematical representations?

Certainly, here are some commonly used activation functions in machine learning along with their mathematical representations:

### 1. Sigmoid Function:

f(x) = 1 / (1 + e^(-x))

The sigmoid function is an activation function that takes a real-valued number as input and returns a value between 0 and 1. It is defined by the equation f(x) = 1 / (1 + e^(-x)). The function has a characteristic S-shaped curve, and its output is used to represent a probability-like value for the input. The function is commonly used in binary classification tasks, where the output represents the probability of belonging to one of two classes.

### 2. Rectified Linear Unit (ReLU) Function:

f(x) = max(0, x)

The ReLU function is an activation function that sets all negative values of the input to zero and leaves all non-negative values unchanged. It is defined by the equation f(x) = max(0, x). This function is commonly used in deep neural networks because it is computationally efficient and does not suffer from the "vanishing gradient" problem that other activation functions can experience.

### 3. Leaky ReLU Function:

f(x) = max(0.01x, x)

The leaky ReLU function is similar to the ReLU function but with a small slope for negative values. It is defined by the equation f(x) = max(0.01x, x). This function is used to overcome the "dying ReLU" problem that can occur when the ReLU function outputs zero for a large number of inputs.

### 4. Parametric ReLU Function:

f(x) = max(alpha*x, x), where alpha is a learnable parameter

The parametric ReLU function is a variant of the ReLU function that includes a learnable parameter alpha. It is defined by the equation f(x) = max(alpha*x, x), where alpha is a learnable parameter. This function can help improve the performance of deep neural networks.

### 5. Exponential Linear Unit (ELU) Function:

f(x) = x if x >= 0, f(x) = alpha*(e^x - 1) if x < 0, where alpha is a hyperparameter

The ELU function is similar to the ReLU function but with a smoother transition around zero. It is defined by the equation f(x) = x if x >= 0, f(x) = alpha*(e^x - 1) if x < 0, where alpha is a hyperparameter. This function is designed to address the vanishing gradient problem and can improve the performance of deep neural networks.

### 6. Softplus Function:

f(x) = log(1 + e^x)

The softplus function is a smooth approximation of the ReLU function. It is defined by the equation f(x) = log(1 + e^x).

This function is used in deep neural networks as an alternative to the ReLU function because it is differentiable at zero and provides a smoother gradient.

### 7. Hyperbolic Tangent (Tanh) Function:

f(x) = (e^x - e^(-x)) / (e^x + e^(-x))

The hyperbolic tangent function is an activation function that maps the input to a value between -1 and 1.

It is defined by the equation f(x) = (e^x - e^(-x)) / (e^x + e^(-x)).

This function is commonly used in recurrent neural networks (RNNs) because it is sensitive to the magnitude of the input and can be used to control the flow of information through the network.

### 8. Swish Function:

f(x) = x * sigmoid(x)

The Swish function is a relatively new activation function that is similar to the sigmoid function but has a learnable parameter beta. It is defined by the equation f(x) = x * sigmoid(beta*x). This function has been shown to outperform other activation functions on a variety of deep learning tasks.

## Note

There are many other activation functions that can be used depending on the problem at hand, but these are some of the most commonly used ones.

~34MB
~373K SLoC