Some properties of difference elliptic operators 277
(12)
and
(13)
with
(14) [y, v] = (y, v) + hi h2 [
4
y(O, 0) v(O, 0) + y(O, 12 ) v(O, 12 )
+ y(l 1 , 0) v(l 1 , 0) + y(l 1 , 12 ) v(l 1 , 12 )]
N2-I
+ ';^1 L [y(O, i 2 h 2 ) v(O, i 2 h 2 )
i2=2
N 1 -J
+~^2 2= [y(ilhl,o)v(ilhl,o)
'1 =2
the inner product (y, v) being understood in the sense of (7).
0
- Properties of difference operators. Introduce the space rlh of all grid
functions defined on the grid wh = wh + ih and vanishing on the boundary
ih and the space s:th comprising all the functions defined on w h. The inner
product in the space s:th is defined to be
(15) (y,v)= L y(x)v(x)h 1 h 2 •
xEwh