/>A7I /.V(./'(»/.V/ /MriD.IXCI Oh llfOMISII CIHll ll\ 



l>\ .1 rink- taiiKiMit Id tin- xtTliial .ixis with its ii-ntrr \iTlif.iliy .i1m>\c 

 ilu- doiiblf r(M)t. If, for exaniplf, the rl<)iil>ii' root tli'M-rihi's a circle 

 alK)ut till- origin tlirouj;h tlu- [niinl a on the Ncrtical axis, the corce- 

 spondinK circle is taiii;cnt to the vertical axis at a. Thus in Fi({. -if, 



Kig. J — Domain of the poles of the tlrix lnK-|>oint impedance of a two-mesh circuit 



with (al one pair of roots on the axis of imaginaries, <l>i one pair of rootsnearthe 



axis of imai;in, tries, ici two pairs of equal roots, .md i<li two p.iirs of riM>ts with 



e<]ual angles. 



lor df)uble roots at .ii, Bi, C\, the corresponding domain is bounded 

 by the circles .4, B, C, respectively. The centers of these circles are 

 all on the horizontal line through a. and the double roots are selected 

 so as to space the centers uniformly. If all four roots are real and 

 e(|ual, the domain is bounded by a circle P tanKeiit to the vertical 

 axis at a and to the horizontal axis at this fourfold r<«>l />i. If the 



