xii Prefuce Although we have written this book prirriarily for students, we are convinced that it will also be nscfnl for practitioners An engineer who wants to brush up quickly on some subj will apprvciatc the easy rcadability of this text, its practice-orient etl prt ntation, and its rnaiiy examples This book evolved out of a course on systems theory arid the corresponding laboratory excwises at the F1ieclric.11Alexander University in Erlcuzgeri-~~rriherg The course is compulsory for students of electrical engineering iii 1he fifth semester A s such, the rnt31mhl in this book can be worked through complet ely i n about 50 hoixrs of lecture8 and 25 hours of exercises ?Ve assume knowledge of the f h dumerit als of crigiricering iiiathornatics (diEerentia1 anti iiitcgral ral~ulub,liircnr algebra) and basic luio&cdge 01electrical circuits Assuming that, t?hismathematical knowledge hi^ been ucquired earlier, the material is also suitable for iise in the third or fourth semester An engineering curriculum often encompasses complex funct ion 1heoi.y and probability theory as well: dt hough thesc fields are lrelpfid, we not assume familiarity with thern This book is altio siiitablc for self-study Assimiing full-time conwntrated work the materiiil can be covned in four to six weeks Our presentation bcgins with continuous signals arid systems Contrary to some other books that first introduce detailed forms of description for signals and only rnuch l a t c ~add systems, wF treat sigiials and s y s t e m in parallel The purpose of dcscribiiig sigiials by meaiis of their Lup1tix:e or Pouricr Lr;zrisforxnat,ioIis becomcs evident o n l ~through the characteristics of lincar, tinie-inwriant syst,t>ms T n our presentation we ernphabisc tkic clcar concept of Rigtm functions whose form is not changed by systems To take into account initial staks, we use state space descriptions which elegantly allow us to couple XI external and an interrial cornponcnt of the systcw response After covering sampling we int,roduce timc-discrete signals arid svstenis iLrld so cxtorid (,liec.oncopts fariiiliar from thc conlinuous c asc" r T l ~ r w aftcr discrete and contimioils sigials and systems are treated together Finally we discuss random signals, which tire very important today To avoid the arduous m d seldom perfect step of correctiiig camera-ready copy, wti liaridlcd the layout of the book ourselves a(, the university All formulas ilritl most of the figures were typeset in LaTeX and then transferred onto overhead slidox I W We itre most g r a ~ eful that mere used h r two y e t m in the? nte criticism Inelped us to to some 200 registered students wh debug the presentation and the typcset equations T n addition, one yea's students read thc first version of the manuscript and suggested diverse irnprovernents Finally iiiinie~oiiswaders of the Cerrnaii wrsion r cpnrl,ed typographic erioib arid sent comments by e-mail Our student, assistimts Lutz and Alexander Larnpe Sl,q)h~mGiidde A'Iarioxi Schahert, Stcfan von der Mark a i d Ilubert Itubcnbauer derrionstraled trernvndous commitment in typesettiiig and correcting the book as well as the solutions to the rcises We thank Ingrid Biirtsch, who typed and corrected a large portion of text, R S well as Susi Kosdiiiy, who pxodiiced niuny figures