Implementation of parameterized soft-exponential activation function on MNIST dataset. In this implementation, the parameters are the same for all neurons initially starting with 1. The soft-exponential function is a good choice for neural networks that have a lot of connections and a lot of neurons.
This activation function revolves around logarithmic, linear and exponential behaviour.
The equation for the soft-exponential function is:
From a paper by A continuum among logarithmic, linear, and exponential functions, and its potential to improve generalization in neural networks, here in Figure 2, the soft-exponential function is shown as a logarithmic function. This is not the case.
The real figure should be shown here:
Here we can see in some cases the soft-exponential function is undefined for some values of (alpha,x), (alpha,x) is not a constant.
Here comes the tricky part. The soft-exponential function is defined for all values of alpha and x. However, the logarithm is not defined for negative values.
In the issues under Keras, one of the person has suggested to use the inverse function of sinh() instead of the log().
Starting with an initial value of 1, the soft-exponential function was steep at the beginning and it is more gradual at the end. This was a good idea.