Geoscience Reference
In-Depth Information
Formulas ( 2.67 ) and ( 2.68 ) give a recurrent estimation for error. From them it is
possible to obtain an error estimation applicable to the entire interval [t0,T]: 0 ,T]:
h
i
hP 1
p 0
k
k
E k e 0 ð 1 þ hp 0 Þ
þ
ð
1 þ hp 0
Þ
1
;
where the following notations are introduced
;
ð j Þ
i
h ¼ max
k
h k ;
E k ¼ max
i ; j
e
ð t k Þ
M ¼ max
i
M i ;
m ¼ min
s
m s ;
þ l 1
s¼1
h m 1
ðm þ 1 Þ! ;
p 0 ¼ mM h m 1
m!
h s 1
s
P 1 ¼ M
;
l ¼ max
s
m s
!
2.12.5.4 Solutions of Equations with Known Moments on the Right Side
Let us consider a particular case of Eq. ( 2.49 ):
L½y ¼y ð n Þ þ X
n
p i y ð n i Þ ¼ f ð x Þ;
x 0
ð 2
:
69 Þ
i¼1
where p i
is the constant coef
cients,
f(x) is a single-valued and differentiable
function, f(x)
0asx
and its moments are known:
Z 1
x m f ð x Þ dx
M m f ð x Þ ¼
\ 1;
m ¼ 0
;
1
; ...;
m
ð 2
:
70 Þ
0
It is necessary to solve the Eq. ( 2.69 ) with the following initial conditions:
y ð s Þ ð x 0 Þ ¼y ð s Þ
ð s ¼ 0
;
1
; ...; n 1 Þ
0
We shall approximate f(x) in the following manner:
f ð x Þ exp ð kx Þ X
m
a i x i
¼ P m ð x Þ exp ð kx Þ;
ð 2
:
71 Þ
i¼0
where m > 0 is an integer, k > 0 and a i are constants to be determined. Then, from
( 2.70 ) and ( 2.71 ) we have
"
# dx ¼ X
Z 1
x m exp ð kx Þ X
m
m
a i ðm þ i Þ!
k i þ 1
M m f ð x Þ ¼
a i x i
i¼0
i¼0
0
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