ELU

ELU is an acronym used in several fields, and its meaning depends on the context. In machine learning, ELU most commonly refers to the Exponential Linear Unit, an activation function used in neural networks.

The ELU function is defined as f(x) = x for x > 0 and f(x) = alpha*(exp(x) - 1) for x <= 0, where alpha is a positive parameter. Compared with the rectified linear unit (ReLU), ELU allows negative activations, which can reduce bias shift in the activations and improve gradient flow during training. ELUs are continuous and differentiable, and their smooth behavior near zero can help learning progress in some architectures. A typical choice for the parameter is alpha = 1, though researchers explore other values to suit specific tasks. In practice, ELUs can speed up training and improve accuracy on certain datasets, at the cost of additional computation due to the exponential term.

In online knowledge communities, ELU stands for English Language & Usage, the Stack Exchange site dedicated to questions about English grammar, usage, vocabulary, etymology, and style. It hosts user-generated questions and answers, with voting and moderation to maintain quality discussions about language.

In other contexts, ELU may be used as an acronym for additional entities or concepts, depending on the field. The definitions above reflect two of the most common and widely recognized uses.