In this volume I shall give some guidelines for solving problems in the theories of Fourier series and Systems of Differential Equations and eigenvalue problems. The reader should be aware of that it has never been my intention to write an alternative textbook, since then I would have disposed of the subject in another way. It is, however, my hope that this text can be used as a supplement to the normal textbooks in which one can find all the necessary proofs. This text is a successor of Calculus 1a, Functions of one Variable and Calculus 3b, Sequences and Power Series, which will be assumed in.
