H(s) usually is a ratio of two polynomes containing s, by means of partial-fraction-expansion obtain H(S) N(S) D(s) S-P CB(=C1∑k|=∑ s-P i=1 815-9 The complex-frequency plane H(S) N(S) (S-x1)(S-z2)…(s-zmn) D(S) 0 (S-p1)(S-p2)…(S-Pn) Ho real number zeros P,p2… Pn polesH(s) usually is a ratio of two polynomes containing s, by means of partial-fraction-expansion obtain = − = = n i i i s p k D s N s H s 1 ( ) ( ) ( )   = = − − = − = = n i p t i n i i i i k e s p k h t L H s L 1 1 1 1 ( ) [ ( )] [ ] §15-9 The complex-frequency plane ( )( )...( ) ( )( )...( ) ( ) ( ) ( ) 1 2 1 2 0 n m s p s p s p s z s z s z H D s N s H s − − − − − − = = H0 real number z1, z2, … zm zeros p1, p2, … pn poles