The orientation and perspective of this book remains numerical linear algebra for applications in statistics. Computational considerations inform the narrative. There is an emphasis on the areas of matrix analysis that are important for statisticians, and the kinds of matrices encountered in statistical applications receive special attention. This book is divided into three parts plus a set of appendices. The three parts correspond generally to the three areas of the book’s subtitle—theory, computations, and applications—although the parts are in a different order, and there is no firm separation of the topics.