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Fig. 15.1
Condition number
for hat functions (
top
)and
wavelets with preconditioning
(
bottom
)
(L
5
) GMRES iterations
,
the fully discrete Galerkin scheme
with incomplete GMRES gives
using in each time step
O
p
−
1
CN
−
s
L
U
dG
(T )
(
log
2
N
L
)
(d
−
1
)s
+
ε
,s
u(T )
−
L
2
(G)
≤
:=
p
−
1
+
1
.
dp
−
Remark 15.4.8
The numerical experiments in the examples below show that the
convergence rate of Theorem
15.4.7
is likely not optimal. Indeed, the experiments
suggest that the error measured in
L
2
satisfies the same estimate as the sparse grid
projector
P
L
(at least for the wavelets of Example 12.1.1), i.e.
CN
−
p
L
U
dG
(T )
(
log
2
N
L
)
(d
−
1
)(p
+
1
/
2
)
+
ε
u(T )
−
L
2
(G)
≤
;
compare with Theorem 13.1.2.
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