This lecture covers the gradient method for solving optimization problems without constraints. The instructor explains the concept of minimizing a functional F from Rn to R, emphasizing the importance of the gradient being zero at the minimum point. Various examples are provided, including least squares regression and the representation of data points using basis functions. The lecture also discusses the conditions for convergence of the gradient method, highlighting the significance of choosing an appropriate step size. The instructor illustrates the relationship between the gradient and the contours of the function, explaining how to iteratively approach the minimum. The mathematical foundations are laid out, including the derivation of the gradient and the implications of the Hessian matrix. The lecture concludes with a discussion on the practical applications of the gradient method in machine learning, emphasizing its effectiveness in high-dimensional spaces. The instructor encourages students to understand the theoretical aspects while also considering practical implementations in real-world scenarios.