190 
PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 28 
then we have 
_ ao 
2 
a \ 
0 
he 
de 
2 
-be 
bh? 4 ¢2 
— 
"eos 
ve 
L_ 
and hence 
(A5) gd + RR 
b +c +29 —(bc+g) oO co] 
(be+g) b'+c+29 —(be+9) … 
—(be+g) b’+c+2g 
\ 
which is an infinite band matrix in the infinite-horizon case. 
The derivations will be somewhat simplified if we write (A.5) 
in the following form: 
(A.6) 
ha 1 
gA+RR 
=2(bc +9) 
thr 
he + q) 
The matrix on the right [disregarding the factor 2 (bc+ g)] 
can be written as a scalar (p) times the product of two simple 
71 Theil - pag. 26