Wiley signals and systems e book TLFe BO 144

7.1 F'irstr Order syst>cms I29 Tlir initial wluc i s tlw d u c of the ou-lpul sigclul itt (ime I- - For sigrirtls wit11 a step at t = O this is the v i h c of the right-hand limit y(O+), regni(iI(~~s of wlrct1tt.r or nott thc plus sign is written