| Nowadays matrices are used in many fields of science, Accordingly they have become standard tools in statistics, econometrics, mathematics, engineering and natural sciences textbooks, In fact, many textbooks from these fields have chapters, appendices or sections on matrices, Often collections of those results used in a book are included, Of course, there are also numerous books and even journals on matrices, For my own work I have found it useful, however, to have a collection of important matrix results handy for quick reference in one source, Therefore I have started collecting matrix results which are important for my own work, Over the years, this collection has grown to an extent that it may now be a valuable source of results for other researchers and students as well. To make it useful for less advanced students I have also included many elementary results.
The idea is to provide a collection where special matrix results are easy to locate, Therefore there is some repetition because some results fit under different headings and are consequently listed more than once, For example, for suitable matrices A, Band C, A(B + C) = AB + AC is a result 011 matrix multiplication as well as on matrix sums, It is therefore listed under both headings, Although reducing search costs has been an important objective in putting together this collection of results, it is still possible that a specific result is listed in a place where I would look for it but where not everyone else would, because too much repetition turned out to be counterproductive, |