Description: Functional gradient is a fundamental concept in optimization, especially in the context of machine learning. It refers to a method that considers the functional form of the objective to be optimized, allowing the calculation of how small variations in the model parameters affect overall performance. In the realm of recurrent neural networks (RNNs), where data is sequential and information is maintained through hidden states, the functional gradient becomes a crucial tool for adjusting the weights of the network. This approach enables the model to learn temporal patterns and relationships in the data, facilitating continuous performance improvement as it trains on more data. The ability to efficiently compute the functional gradient is essential for the convergence of the optimization algorithm, as it allows for precise adjustments to the model parameters. In summary, the functional gradient is a key component in training machine learning models, as it provides the necessary information to guide the optimization process toward more effective and accurate solutions.