A learning rate is a training hyperparameter that controls how large a step model weights take during backpropagation. Small steps can make training slow; large steps can make updates chaotic. section 9.18 section 11.35
The rate is part of gradient descent: after calculating the gradient, training moves in the opposite direction, with the learning rate determining the step size. section 9.26
Choosing a learning rate involves balancing speed, stability, and experimentation:
- Use a slow rate for smaller, steadier updates, while recognizing that training may take longer. section 9.18
- Treat a high rate cautiously because dramatic weight changes can produce chaotic training. section 9.18
- Adjust the rate when training stagnates, using experimentation or a tuning strategy. section 9.18 section 11.35
Comparing candidate values
A tuning run might compare learning rates of 0.01, 0.001, and 0.0001. Grid search trains every selected combination, while random search tests a fixed number of randomly chosen combinations and can explore more efficiently. section 11.35















