For the book, you may refer: https://amzn.to/3aT4ino
This lecture explains how to construct the Hessian Matrix of a function and discusses the positive, negative definiteness of it.
Previous lecture:
Quadratic form: https://youtu.be/6jjTLDX_JOk
Hessian Matrix: https://youtu.be/mJB-XLV0QJc
Convex & Concave function: https://youtu.be/nZ7vjo2dQ1o
Maxima & Minima of the function: https://youtu.be/gJHgIcMeS2M
