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Gradient descent

Gradient descent updates parameters in the direction opposite the local loss gradient. The learning rate controls step size; convergence behavior also depends on curvature, noise, scaling, and optimizer state.

\theta_{t+1}=\theta_t-\eta\nabla_\theta L

Overview. Gradient descent updates parameters in the direction opposite the local loss gradient. The learning rate controls step size; convergence behavior also depends on curvature, noise, scaling, and optimizer state.

Mechanism and context. The gradient gives the local direction of increasing loss, so subtracting a learning-rate-scaled gradient proposes a lower-loss parameter update. In a neural network this operation is repeated over batches, while the optimizer determines how present and past gradient information shape each step.

Practical use. Use the formula as a debugging map: inspect the loss, gradient scale, learning rate, and parameter change separately. A flat or unstable training curve may reflect the objective, data scale, numerical behavior, or update rule rather than a vague failure of the model.

Related reading. Read Backpropagation for how the gradient is computed through layers, Cross-entropy for a common training objective, and Adam for an adaptive update rule that maintains moment estimates.

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