Otimizador Adam
O Adam Optimizer, abreviação de Estimativa de Momento Adaptativa, is a popular algoritmo de otimização used in treinar modelos de aprendizado de máquina, particularly in deep learning. Developed by D.P. Kingma and J.B. Ba in 2014, Adam combines the advantages of two other extensions of stochastic gradient descent (SGD): AdaGrad and RMSProp.
Adam adapta a taxa de aprendizado for each parameter individually, which helps in optimizing the performance of the model during training. It does this by calculating two moving averages: the first moment (mean) and the second moment (uncentered variance) of the gradients. This allows Adam to adjust the learning rate based on the momentum of the gradients, which stabilizes the training process.
One of the key features of Adam is its ability to handle sparse gradients, making it particularly effective for problems such as processamento de linguagem natural and computer vision. It also includes bias correction terms to counteract the initial bias towards zero in the first moments, especially in the early stages of training.
Adam is characterized by several hyperparameters, including the learning rate (often denoted as α), β1 (the decaimento exponencial taxa para o primeiro momento), e β2 (the exponential decay rate for the second moment). Default values are often set to α = 0.001, β1 = 0,9, e β2 = 0,999, que funcionam bem em muitos cenários.
Overall, the Adam Optimizer is widely used due to its efficiency, ease of use, and robustness, making it a go-to choice for many practitioners in the field of machine learning.