👉 Hessians are a type of matrix that is used in linear algebra and functional analysis. They are often associated with linear operators on vector spaces, particularly when working with matrices or tensors. A vector space V over a field F (such as real numbers or complex numbers) has a basis consisting of vectors v1, v2, ..., vn such that the collection of all possible linear combinations of these vectors is denoted by {v1, v2, ..., vn}. This collection forms a basis