
120
Z. Drmal and K. Veseli~
In the nodal analysis of e.g. electrical resistance network the
node conductance
matrix of
the Julie bridge is
TAB ~" TAD n c TEA --TAB
0
--TAD
K
= --TAB TAB q-
7BC -[-
7BE
--TBC 0
0 --TBC 7BC @- 7CD "4- 7CE --TCD "
--TAD
0
--TCD TAD 2r 7CD 2r ")'DE
Then K =
A~A
with
A
~V~7~ - ~V'q~ o o
o o -~
o ~ - ~Vq-~ o
o o ~
-~
o o o
o ~ o o
o o ~ o
o o o
The upper 4 x 4 part of A is an element from 7)4 and can be transformed into the triangular
form in a forward stable way. To get the triangular factor of K the update by the lower
4 x 4 part