The Mathematical Model

Abstract

Throughout the book, Latin and Greek subscripts take the values 1, 2, 3 and 1, 2, respectively, and the convention of summation over repeated indices is understood. For simplicity, we denote by I both the identity matrix on any space of square matrices and the identity operator on any space of functions. Also, we denote the transpose of a matrix X by $X^{\mathrm{T}}$ and the derivatives of a function f = f(x _i ) by