Η θεωρητική-αριθμητική-των-πυθαγορείων - ΤΟΜΑΣ ΤΕΫΛΟΡ, ΕΚΔ. ΙΑΜΒΛΙΧΟΣ
Αριθμητική Ανάλυση
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Transcript of Αριθμητική Ανάλυση
-
.
y
x{f( )
x2 x1 x0
M0
P0
y=f(x)
f(b)
b
}
2008
-
.
2008
2
-
1 7
1.1 . . . . . . . . . . . . . . . . . . . . . . . . 7
1.2 . . . . . . . . . . . . . . . . . . . . 8
1.3 13
1.4 . . . . . . . 15
1.5 . . . . . . . . . . . . . . . . . . 17
2 24
2.1 . . . . . . . . . . . . . . . . . . . . . . . . 24
2.2 Bolzano . 25
2.3 (Regula Falsi) . . 31
2.4 . . . . . . . . . . 33
2.4.1
. . . . . . . . . . . . . . . . . . . . . 41
2.5 Newton-Raphson . . . . . . . . . . . . . . 43
2.5.1 Newton-Raphson . . . 44
2.5.2 Newton 2 Bailey 54
2.6 . . . . . . . . . . . . . . . 55
2.7 - Aitken . . 58
2.8 . . . . . . . . . . . . . . . . 59
2.8.1 Horner . . . . . . . . . . . . . . 61
2.8.2 p(x) 63
3 -
66
3.1 Gauss . . . . . . . . . . . 66
3.1.1 Axk = bk, k = 1(1) . . . . . . . . 733.1.2 A1 . . . . . . . . . . . . . . 733.1.3 detA . . . . . . . . . . . . . 73
3
-
3.1.4 Gauss . . . . 74
3.1.5 Gauss 75
3.1.6 . . . . . . . . . . . . . . 79
3.1.7 Gauss
. . . . . . . . . . . . . . . . . . . . . 82
3.2 Jordan . . . . . . . . . . . 84
3.2.1 Jordan -
. . . . . . . . . . . . . . . . . . . 90
3.2.2 . . . . . . . . . 92
3.3 LU . . . . . . . . . . . . . . . . . . . . . 97
3.4 LU . . . . . . . . . . . . . 107
3.4.1 Choleski . . . . . . . . . . . 117
3.5 LU . . . . . . . . . . 118
3.5.1 LU - . . . . . . . . . . . . . . . . . . . . . . . 121
3.5.2 . . . . . . . . . 123
3.5.3 LU . 131
3.6 Norms . . . . . . . . . . . 135
3.7 . . . . . . . . . . . . . . . . . . . 143
4
146
4.1 . . . . . . . . . . . . . . . . . . . . . . . . . . 146
4.2 . . . . . . . . . . . 149
4.3 . . 164
4.4 Jacobi165
5 -
168
5.1 . . . . . . . . . . . . . . . . . . . . . . . . . . 168
5.2 . . . . . . . . . . . . . . . . 169
5.3 . . . . . . . 175
5.4 . . . . . . . 177
5.5 . . . 179
5.5.1 Aitken . . . . . . . . . . . . . . 179
5.5.2 Rayleigh . . . . . 180
5.5.3
Rayleigh . . . . . . . . . . . . . . . . . . . . . 182
4
-
5.5.4 (Shift of O-
rigin) . . . . . . . . . . . . . . . . . . . . . . . 183
5.6 . . . . . . . . . 184
6 187
6.1 . . . . . . . . . . . . . . . . . . . . . . . . . . 187
6.2 . . . . . . . . . . . . . . . . 187
6.3 . . . 191
6.3.1 -
Newton . . . . . . . . . . . . . . . . 191
6.3.2 -
Newton . . . . . . . . . . . . . . . . 193
6.4 . 195
6.4.1 Lagrange . . . . . . . . 195
6.4.2 . . . 197
6.4.3 . . . . . . . . . . . . . . 200
6.4.4 Newton -
. . . . . . . . . . . . . . . . . 202
7 207
7.1 . . . . . . . . . 207
7.2 . . . . . . . . . . . . . . . . . 210
8 218
8.1 . . . . . . . . . . . . . . . . . . . . . . . . . . 218
8.2 -
. . . . . . . . . . . . . . . . . . . . . . . . . . . 218
8.3 -
. . . . . . . . . . . . . . . . . . 222
8.4 . . . . . . 225
8.5
. . . . . . . . . . . . . . 228
8.6 . . . . . . . . . 229
9 231
9.1 . . . . . . . 231
9.2 . . . . . . . . 237
9.3 . . . . . . 239
9.4 . . . . . . 241
9.5 Romberg . . . . . . . . . . . . . 244
5
-
9.6 Gauss . . . . . . . . . . . . . . . 247
10 249
10.1 . . . . . . . . . . . . . . . . . . . . . . . . . . 249
10.2 Euler . . . . . . . . . . . . . . . . . . 250
10.3 Taylor . . . . . . . . . . . . . . 251
10.4
Euler Taylor . . . . . . . . . . . . . 260
10.5 -
. . . . . . . . . . . . . . . . . . . . . . . . . 263
10.6 Runge-Kutta 2 . . . . . . . . 264
10.7 Runge-Kutta 4 . . . . . . . . 266
10.8 . . . . . . . . . . 269
10.9 -
. . . . . 272
10.10
. . . . . . . . . . . . . . . . . . . . . 274
10.11
. . . . . . . . . . . . . . . . 276
6
-
1
1.1
-
.
1. -
.
,
.
2. .
.
3. . ,
, -
. -
.
4. .
.
,
.
7
-
1. x x,
|x x|
|x x||x| , x 6= 0.
1.2
-
. 432.52
4 102 + 3 101 + 2 100 + 5 101 + 2 102
101.11
1 22 + 0 21 + 1 20 + 1 21 + 1 22 = 5.75
(101.11)2 = (5.75)10
() - .
.
-
.
.
-
(bit) . -
n bits
8
-
,
:
n (111 . . . 1)2 = 1 2n1 + 1 2n2 + + 1 20 = 2n 1.
n = 15 215 1 = 32.767. , [(2n 1), 2n 1] .
.
-
-
.
-
. ,
15.546 = 0.15564 102.
, x ( 6= 0)
x = x 10e (1.1) e , (exponent)
x (mantissa). 0.1 x < 1. ,
x = x e, (1.2)
x = (0.a1a2 . . . an). (1.3)
ai, i = 1, 2, . . . n
0 ai 1, a1 6= 0. (1.4)
:
m e M (1.5)
9
-
m . m = M m = M 1. (1.3) n ,
n .
= 2. 1.1 64 32
bits .
{{{ {x x ee bits2-24 bits25-32bits2-12 bits13-64
64 bitCDC6000
1.1: . -
(bit) 0 1
.
(1.2) (floating point).
[s, L]
. = 2, x - n
|e| M. (1.6) x :
n (0.10 . . . 0)2 x
n (0.11 . . . 1)2
10
-
1
2 x 1 2n (1.7)
s =1
2 2e x 2e = |x| (1 2n) 2e = L < 2e
2e1 |x| < 2e. (1.8) x
x = (0.1a2a3 . . . an)2
e = M,M+1, . . . ,M1,M , 2n1 x. x 2n1 x [2e1, 2e) (2e,2e1] (. 1.2)
- L
( )
}
[]
}
)[ [ ]. . .[ ]. . . ( ]}} e = - M e = - M e = - M+1e = - M+1
0 s 2s 4s L- s- 2s- 4s
1.2: .
1
[2e1, 2e) (2e,2e1]. -
1.2 -
.
(1.6) (1.7), -
.
[L,s] [s, L]. x |x| > L
(overflow). |x| < s (underflow). -
x
11
-
,
e .
= 2, n = 3, m = 1, M = 2, .
(1.2) - (1.3)
x = x 2e, x = (0.1a2a3)2 0 ai 1, i = 2, 3. x (0.100)2, -
(0.001)2. e :0.100, 0.101, 0.110 0.111 e = 1, 0, 1, 2 :
(0.100)2 21 (0.101)2 21 (0.110)2 21 (0.111)2 21(14) ( 5
16) ( 6
16) ( 7
16)
(0.100)2 20 (0.101)2 20 (0.110)2 20 (0.111)2 20(12) (5
8) (6
8) (7
8)
(0.100)2 21 (0.101)2 21 (0.110)2 21 (0.111)2 21(1) (5
4) (6
4) (7
4)
(0.100)2 22 (0.101)2 22 (0.110)2 22 (0.111)2 22(2) (5
2) (6
2) (7
2)
,
. :
04
1
2
11
4
5
4
6
4
7
2
52
2
73
4
1-
2
1-
4
5-
4
6-
4
7-
2
5-
2
7- -1-2-3
(14, 0)
(0, 14). , -
.
.
12
-
1.3 -
x = (0.a1a2 . . . anan+1 . . .) e, a1 6= 0 (1.9)
(=2, 8, 10, 16). n, .
: x; -
x (- 1.3). 1.3 (),
x x an+1 . . . (. (1.9)),
x = (0.a1a2 . . . an) e. (1.10)
x
xx
x
xx
(a) (b)
1.3: x (x, x ).
1.3(b), x
x x (0.00 . . . 01) =
n,
x =((0.a1a2 . . . an) +
n) e. (1.11)
(rounding up). -
.
()
.
13
-
() 3.1, -
|x x| 12|x x| =
(1
2n
) e (1.12)
|x x||x|
12n ex e =
12n
x
12n
1=
1
2n+1. (1.13)
(1.12) (1.13)
(b) 1.3. -
x fl (x). (1.12) (1.13)
|x fl (x)| 12n e (1.14)
|x fl (x)|
|x| 1
2n+1, (1.15)
. (1.14) (1.15)
.
=fl (x) x
x,
fl (x) = (1 + )x (1.16)
(1.15)
|| 12n+1. (1.17)
(machineunit), , (1.16) fl (x) x.
(chopping). ,
x , x (. .
14
-
1.3). -
, x x,
|x fl (x)| en (1.18) |x fl (x)|
|x| n+1. (1.19)
(1.14), (1.15) (1.18) (1.19)
:
1.
.
2.
-
, .
Wil-
kinson.
. -
.
1.4 -
.
S =
ni=1
xi (1.20)
xi - . ,
15
-
S2 = fl (x1 + x2)
3 ...,
S3 = fl (x3 + S2)S4 = fl (x4 + S3)...
Sn = fl (xn + Sn1)
(1.21)
Sn S. (1.16),
S2 = (x1 + x2) (1 + 2)S3 = (x3 + S2) (1 + 3)...
Sn = (xn + Sn1) (1 + n)
(1.22)
|i| 12n+1, i = 2, 3, , n.
(1.22)
S2 = (x1 + x2) + (x1 + x2) 2S3 = [(x1 + x2 + x3) + (x1 + x2) 2] (1 + 3)
= (x1 + x2 + x3) + (x1 + x2) 2 + (x1 + x2 + x3) 3 + (x1 + x2) 23
, 23 2, 3, -
S3 (x1 + x2 + x3) + (x1 + x2) 2 + (x1 + x2 + x3) 3.
Sn ni=1
xi+(x1 + x2) 2+(x1 + x2 + x3) 3+. . .+(x1 + x2 + . . . + xn) n
(1.20)
Sn S x1 (2 + 3 + . . .+ n) + x2 (2 + 3 + . . .+ n)+x3 (3 + 4 + . . .+ n) + . . .+ xnn
16
-
|Sn S| . |x1| (|2|+ . . .+ |n|) + |x2| (|2|+ . . .+ |n|)+ |x3| (|3|+ . . .+ |n|) + . . .+ xn |n| . (1.23)
(1.23) -
|S Sn| - : ,
,
|x1| |x2| |x3| . . . |xn| .
, (1.23)
i xi.
1.5
x x (1.14) (1.15), .
|x| = |x x| 1210d
(1.14), x x d . x d ( x). x 6= 0,
.
,
().
|x| =xx
5 10s, (1.15), x x s . x s .
17
-
. -
.
() x = 28.254, x = 28.271, () x = 0.028254, x = 0.028271() x = e, x = 19/7 () x =
2, x = 1.414 () x = log2, x = 0.7.
()
|x| = |x x| = |28.254 28.271| = | 0.017|= 0.17 101 < 0.5 101.
, x .
|x| = |xx| = 0.17 10
1
28.254=
0.17 1010.28254 102 0.602 10
3 < 5 103
x .()
|x| = |x x| = |0.028254 0.028271| = 0.000017 0.17 104 < 0.5 104
|x| = |xx| = 0.17 10
4
0.28254 101 0.602 103 < 5 103
x .
10
,
[. () ()].
( ;)
() ,
|x| = |x x| = |e 19/7| = |2.718281 2.714286| 0.003995= 0.3995 102 < 0.5 102
18
-
|x| = |xx| = 0.3995 10
2
0.2714286 101 1.4718 103 < 5 103
x , .
()
|x| = |x x| = |2 1.414| = |1.414214 1.414| = 0.000214
= 0.214 103 < 0.5 103
|x| = |xx| = 0.214 10
3
0.1414214 101 1.51 104 < 5 104.
(+,,, /) , - . x y
x = x+ x y = y + y (1.24)
x y . xy
xy = xy xy= (xy xy) + (xy xy) . (1.25)
(1.25) -
xy.
fl (xy) = xy (1.26)
xy , (1.15) (1.26)
|xy xy| 12n+1 |xy| (1.27)
19
-
.
. = , (1.25)
xy = (x y) (x y)= (x x) (y y)
xy = x y
|xy| |x|+ |y| . (1.28) .
1.5.1. -
.
, x y - (, |x| , |x| < 12 104), xy xy 104. x y . , x y - , xy
|x| |y|. = ,
xy = xy xy = xy (x x)(y y)
xy = yx + xy + xy. (1.29)
= / y, y 6= 0,
x/y =x
y x
y=
x
y x x
y y =yx xyy2 + yy
. (1.30)
(1.29) (1.30)
xy xy + yx (1.31)
20
-
x/y yx xyy2
(1.32)
. (1.31) x y xy. , (1.32) x/y x / y.
(. /
-
/ ) -
.
1.5.2.
.
. (1.31) xy
xy =xyxy
=xx
+yy
+xx yy
(1.33)
xy = x + y + xy. (1.34)
|x|, |y|
-
x/y x y
|x/y| . |x|+ |y|. (1.37)
x y s , xy x/y s (;). , -
xy =xyx y =
xx y
yx y =
(x
x y)x
(y
x y)y.
(1.38)
(1.38) x y x y, x/(x y) y/(x y) xy.
.
x1 = 4.54, x2 = 3.00 x3 = 15.0 - . ,
() x1 x2 + x3() x1x2/x3() -
() ();
()
x1, x2 x3 , ,
|x1| 1
2102, |x2|
1
2103 |x3|
1
2101.
22
-
1.5.1
|x1x2+x3| |x1|+ |x2|+ |x3| 1
2102 +
1
2103 +
1
2101
=1
2(101 + 102 + 1)101 = 0.555 101 > 0.5 101.
, -
.
() -
|x1 |, |x2|, |x3| 5 103. 1.5.2
| x1x2/x3 | . |x1|+ |x2|+ |x3 | = 3 5 103 = 5 102.
.
23
-
2
2.1
-
f (x) = 0 (2.1)
f (x) - x. f (x) x. - f (x) .
( -
4). (2.1). -
(2.1) f () = 0. - [a, b] . , - .
,
.
24
-
2.1.1. f (x) C [a, b] 1 f (a) f (b) < 0, (a, b)
f () = 0.
(a, b) (2.1), -. , ,
() -
.
x0 (a, b) ()
x1, x2, . . . - {xn} , n = 0, 1, 2, . . . . - ,
.
-
{xn} , n = 0, 1, 2, . . ..
2.2 -
Bolzano
[a, b] .
, f (x) C [a, b] f (a) f (b) < 0, - (a, b) (2.1). - c0 = (a0 + b0) /2, a0 = a b0 = b. f (c0) = 0, = c0 f (a0) f (c0) < 0. , (a0, c0) -, a1 = a0 b1 = c0, [a1, b1] . f (a0) f (c0) > 0, f (c0) f (b0) < 0 (c0, b0), [a1, b1], a1 = c0
1 Cn [a, b] - [a, b] n-. C0 [a, b] C [a, b] [a, b].
25
-
b1 = b0. (a1, b1) , f (x) (. 2.1).
x
y
y = f(x)
(a, f(a))
a = a0 c0 c2 c1
(b, f(b))
b = b0
b0
b1
b2
a0
a1
a2
c0
c1
c2
2.1:
, -
[a0, b0], [a1, b1] , . . . , [an, bn]
a0 a1 a2 . . . b0b0 b1 b2 . . . a0 (2.2)
f (an) f (bn) 0, n = 0, 1, 2, . . . (2.3)
bn an = 12(bn1 an1) . (2.4)
{an} ,. , {bn} - . (2.4)
bn an = b0 a02n
. (2.5)
26
-
limn
bn limn
an = limn
2n (b0 a0) = 0.
= limn
an = limn
bn
(2.3)
f (x), [f ()]2 0, f (x).
[an, bn], [an, bn]
cn =an + bn
2. (2.6)
| cn| = an + bn2
bn an2 (2.5)
| cn| b0 a02n+1
. (2.7)
> 0,
| cn|
, (2.7), n
b0 a02n+1
n log (b0 a0) log 2
log 2
. (2.8)
- n -
. n [an, bn] ( (2.5)),
27
-
f (x) = 0. - [an, bn] , .
an bn, - (an, bn) f (x). (b0 a0) /2n+1 , .
-
.
f (x) ( ). 2.2 -
[a, b].
y
x
(a, f(a))
(b, f(b))
b
a
c
2.2:
[a, b].
f (x) C [a0, b0] f (a0) f (b0) < 0. n = 0, 1, 2, . . . :
28
-
1. cn =an+bn
2
2. f (cn) = 0 = cn
f (an) f (cn) < 0
an+1 = an, bn+1 = cn
an+1 = cn, bn+1 = bn.
-
|f (c)| < , 12 10k.
c f (x) (. 2). -
c < f (c) < , f (c) y = + y = (. 2.3).
y = +
y =
c
f(c)
x
y
2.3: |f(c)| < .
, |c | < , , c - < c < + , c
29
-
-
x = x = + (. 2.4). , -
c f (c) 2.3 2.4
, c f(c) - . ,
|c | < :
|cn cn1| < (2.9)
|cn cn1||cn| < , cn 6= 0. (2.10)
c
+
y = f(x)
x
y
2.4: |c | < .
. , k , 12 10k+2. , {cn}
30
-
|cn cn1| . (2.10)
( cn 6= 0).
2.3 (Re-
gula Falsi)
-
c . .
.
f (x) C [a, b] f (a) f (b) < 0, [a, b] f (x) = 0. , -, x0 (a, f (a)) (b, f (b)) x (. 2.5).
x1b1 = x0
y = f(x)
b = b0 = b1
(a, f(a))
(b, f(b))
x
y
2.5: -
.
a0 = a b0 = b (a0, f (a0)) (b0, f (b0))
31
-
y f (b0)x b0 =
f (a0) f (b0)a0 b0 . (2.11)
(2.11) y = 0 x = x0
x0 = b0 f (b0) b0 a0f (b0) f (a0) . (2.12)
f (a0) f (b0) < 0, (2.12) x0 . - . f (x0) = 0 = x0. f (a0) f (x0) < 0 (a0, x0) [a1, b1] a1 = a0 b1 = x0. - [a1, b1] x1 (2.12) a0, b0 - a1 b1, . , {xn} , n = 0, 1, 2, . . .
xn = bn f (bn) bn anf (bn) f (an) , n = 0, 1, 2, . . . (2.13)
f (an) f (bn) < 0 f (an) 6= f (bn) xn an < xn < bn bn < xn < an.
-
(2.13) , .
f (x) [a0, b0], f (a0) f (b0) < 0. n = 0, 1, 2, . . . :
1. xn (2.13)
2. f (xn) = 0 = xn
f (an) f (xn) < 0 an+1 = an, bn+1 = xn
an+1 = xn, bn+1 = bn.
32
-
2.4
f (x), x [a, b], f () = 0. g (x) - = g (). g (x) . , f (x) = x3 13x + 18, - g (x) : (a) g (x) = (x3 + 18) /13, (b) g (x) =
(13x 18)1/3 , (c) g (x) = (13x 18) /x2. , = g (), f () = 0.
= g () (fixed-point
problem) g (x).
g (x), x [a, b], f (x). g (x) I = [a, b] g (x) y = x (. 2.6).
a s1 s2 s3 b
a
g(a)
g(b)
b y = x
y = g(x)
2.6: s1, s2 s3 g(x).
I = [a, b], g (x) .
33
-
g (x) I, g (x). , x I, g (x) I. I, g () g (x) I.
2.4.1. x I g (x) I g (x) , g (x) I. - g (x) (a, b) L < 1
|g (x)| L < 1 x (a, b) , (2.14) [a, b] g (x).
. F (x) = g(x) x, F (x) . F (a) = g(a)a > 0 F (b) = g(b) b < 0. F (x) (a, b). F () = 0 g() = g(x). g(a) = a g(b) = b, .
-
I 1 I 2 I 1 6= 2.
g (1) g (2) = g () (1 2)
1 < < 2. , (2.14),
|1 2| = |g (1) g (2)| = |g() (1 2)| L |1 2| < |1 2|
. 1 = 2 [a, b] .
x I, g(x) I, .
2.4.2. ( ) f(x) C[a, b], - c1, c2 [a, b] f(c1) f(x) f(c2) x [a, b]. , f(x) (a, b), - c1 c2 [a, b] f (x).
34
-
2.4.1
g(x) [a, b]. - .
x0 [a, b] {xn}n=0
xn+1 = g(xn), n = 0, 1, 2, . . . (2.15)
{xn}n=0 g(x) ,
= limn
xn+1 = limn
g(xn) = g(limn
xn
)= g() (2.16)
g(x) f(x) = 0. (fixed point
method). f(x) = 0 g(x) - g(x) f(x). , (2.15),
.
-
(.
2.7). xn (2.15), xn+1 = g(xn) y- (xn, g(xn)) y = g(x). (xn+1, xn+1) = (xn+1, g(xn)) y = x. xn+1 - Ox. 2.7 . -
.
g(x) x0. n = 0, 1, 2, . . . :
xn+1 = g(xn)
2.4.1
.
35
-
y = x
x0x2x4x3x10
y
x
y = g(x)
2.7: -
.
2.4.3. g(x) C[a, b] g(x) [a, b] x [a, b]. g(x) (a, b) L < 1
|g(x)| L < 1 x (a, b). (2.17) x0 [a, b],
xn = g(xn1), n = 1, 2, . . . (2.18)
[a, b] g(x).. 2.4.1 -
[a, b]. g [a, b] , {xn}n=0 n 0 xn [a, b]. (2.17)
|xn | = |g(xn1) g()| = |g(n)| |xn1 | L |xn1 | n min(xn1, ) < n < max(xn1, ). -
|xn | L |xn1 | L2 |xn2 | . . . Ln |x0 | .(2.19)
36
-
0 L < 1, limnLn = 0,
limn
|xn | limn
Ln |x0 | = 0
{xn}n=0, (2.18), .
x3 2x2 1 = 0 [2, 3]. xn+1 = 2 + 1/x
2n
x0 [2, 3] .
g(x) = 2 + 1/x2 I = [2, 3]. g(x) I. g(x) = 2/x3, g(x) x [2, 3] m = g(3) = 2+1/9 M = g(2) = 2 + 1/4. , g(x) [2+1/9, 2+1/4] [2, 3] x [2, 3].
|g(x)| = 2x3
14 x [2, 3]. g(x) 2.4.3 xn+1 = 2+1/x
2n, n =
0, 1, 2, . . . x0 [2, 3] [2, 3].
f(x) = x2 x 2 2 -1. = 2 .
f(x) = 0 x = g(x) g(x) f(x), xn+1 =g(xn), n = 0, 1, 2, . . . g(x), :
(a) g(x) = x2 2 (b) g(x) = 2 + x
(c) g(x) = 1 +2
x(d) g(x) = x x
2 x 2m
,m 6= 0.
37
-
(), g(x) > 1 x > 1/2 - (2.17)
= 2. (b),
g(x) =1
22 + x
.
x 0 g(x) 0 0 g(x) 1/8 < 1 (2.17). x k,
2 + x 2 + k 2 + k k k 2, g(x) = 2 + x k k 2. x [0, k], k 2 g(x) C[0, k]
2.4.3. x0 [0, k], k 2, = 2. , x0 = 0,
xn+1 =2 + xn, n = 0, 1, 2, . . .
x1 =2 = 1.41421
x2 =2 + x1 =
3.41421 1.84776
x3 =2 + x2 =
3.84776 1.96157
x4 =2 + x3 =
3.96157 1.99037
x5 =2 + x4 =
3.99037 1.99759
= 2. (c) (d) -
.
2.4.1.
2.4.3, n- n = xn ,
|n| Lnmax{x0 a, b x0}
|n| Ln
1 L |x0 x1| . (2.20)
. (2.19).
, (2.19)
|n| Ln |x0 | Lnmax{x0 a, b x0}
38
-
[a, b]. ,
|x0 | |x0 x1|+ |x1 | |x0 x1|+ L |x0 |
|x0 | 11 L |x0 x1| .
(2.19)
|n| Ln |x0 |
|x0 | - (2.20).
2.4.1
{xn}n=0 Ln/(1 L) L = maxx[a,b] |g(x)|. L, . L . (2.20)
-
.
L = maxaxb
|g(x)| < 1.
|g()| > 1. - xn+1 = g (xn) = g(),
| xn+1| = |g() g(xn)| = |g(n)| | xn| .
xn , |g(n)| > 1, | xn+1| | xn|. |g(n)| > 1. , ,
2.8.
, -
2.4.1.
-
.
39
-
y = x
y = g(x)
x0 x1 x2 x3
y
x
0 < g() < 1
y = x
y = g(x)
x3 x2 x1 x0
y
x
g() > 1
y = x
y = g(x)
x0 x2 x3 x1
y
x
1 < g() < 0
y = x
y = g(x)
x1 x0 x2
y
x
g() < 1
2.8:
2.4.4. g(x) C1[a, b]2 g(x) [a, b]. |g()| < 1, > 0, x0 (a, b) |x0 | < .
. g(x) (a, b) |g()| < 1, - K |g()| K < 1, > 0 x [, +] I, |g(x)| < K. K (2.17) 2.4.3 I. x I,
|g(x) | = |g(x) g()| = |g()| |x | K < 2 [a, b]
40
-
g(x) I x I. 2.4.3 I.
-
, x0, - .
> 0 g(x) = 12(x +
x) x > 0,
x0
.
g(x) = 12(1
x2), g(x) g(x)
x > 0. ,
g(x), = g(
). , g(
) = 0 < 1,
2.4.4
x0 .
2.4.1 -
-
. -
.
.
.
. {xn}n=0 , . c p
limn
|xn+1 ||xn |p = c, (2.21)
{xn}n=0 p, c ( p = 1 c < 1).
41
-
-
n |n+1| |n|p ( : ). p = 1 -, p = 2 , p = 3, ...
-
(2.21).
2.4.5. 2.4.4
1) g(x) p- I(g(x) Cp(I), 2)g(k)() = 0 k = 1, 2, . . . , p 1 gp() 6= 0 p 1, - I x I p .
. (1) g(x) Taylor x = ,
g(xn) = g() +(xn)
1!g() + (xn)
2
2!g() + . . .
+ (xn)p1
(p1)! g(p1)() + (xn)
p
p!g(p)(n)
n xn . 2)
n+1 = xn+1 = g(xn) g() = (xn )p
p!g(p)(n)
limn xn =
limn
|n+1||n|p =
1
p!
g(p)() . (2.22) (2.22)
p.
2)
g(x) x = .
p = 1, |g()| < 1 2.4.4
. p > 1, |g()| = 0 < 1, .
42
-
2.5 Newton-Raphson
Newton-Raphson
f(x) = 0. f(x) - [a, b], f(x) C2[a, b]. xn [a, b] f (xn) 6= 0 |xn | . Taylor
f(x) xn
f(x) = f(xn) + (x xn)f (xn) + (x xn)2
2!f ((x)) (2.23)
(x) x xn. x = (2.23)
f() = 0 = f(xn) + ( xn)f (xn) + ( xn)2
2!f (()) . (2.24)
(2.24),
|xn | |xn |2 ,
0 f(xn) + ( xn)f (xn)
xn f(xn)f (xn)
.
-
{xn}n=0
xn+1 = xn f(xn)f (xn)
, n = 0, 1, 2, . . . (2.25)
Newton-Raphson.
f (xn) 6= 0.
Newton-Raphson
f(x) C2[a, b] - x0 [a, b].
n = 0, 1, 2, . . . - :
xn+1 (2.25)
43
-
2.5.1 Newton-Raphson
x0 Newton-Raphson.
2.5.1. f(x) C2[ , + ], > 0. f() = 0 f () 6= 0, 0 Newton-Raphson x0 I0 =[0, + 0]. .
. 2.4.4 (-
)
g(x) = x f(x)f (x)
.
I0 = [ 0, + 0] :
1. g(x) C1 (I0),
2. g() =
3. |g()| L < 1 L L (0, 1).
f () 6= 0 f (x) I = [ , + ], 1 f (x) 6= 0 x [1, +1]., g(x) [ 1, + 1].,
g(x) =f(x)f (x)
[f (x)]2
f(x) C2[ , + ] g(x) C1[ 1, + 1].
g() =f()f ()
[f ()]2= 0 < 1
g() = . 2.4.4 -
g(x) = x f(x)f (x)
o I1., Newton-Raphson x0 I0 0 1. g() = 0, 2.4.5, .
44
-
2.5.1
Newton-Raphson x0 . , (2.22) p = 2
limn
|n+1||n|2
=1
2|g()| .
g() =f ()f ()
limn
|n+1||n|2
= M (2.26)
M =1
2
f ()f () . (2.27)
(2.26)
|n+1| M2n
|Mn+1| (Mn)21 (Mn1)2
2 . . . (M0)2n
limn |n+1| = 0
|M0| < 1
| x0| < 1M
= 2
f ()f () . (2.28)
(2.28) x0 M . M , x0 Newton-Raphson .
Newton-Raphson.
Newton-Raphson
f () 6= 0 f(xn)
45
-
f (xn) . .
. f(x) k f(x) f(x) = (x )kh(x), x 6= ,
limx
h(x) 6= 0.
2.5.2. f(x) Ck[a, b], k
f() = f () = f () = . . . = f (k1)() = 0
f (k)() 6= 0. , f () 6= 0, -
: f(x) = 0. - , Newton-Raphson ,
.
2.5.3. f(x) C2[a, b] [a, b] f(x) = 0, k > 1, Newton-Raphson , .
. , Ne-
wton -Raphson,
g(x) =f(x)f (x)
[f (x)]2.
f () = 0 - x = . . k > 1, f(x)
f(x) = (x )kh(x), h() 6= 0. (2.29)
f (x) = (x )k1 [kh(x) + (x )h(x)] (2.30)
46
-
f (x) = (x)k2 [k(k 1)h(x) + 2k(x )h(x) + (x )2h(x)] .(2.31)
g() = limx g(x) = limxf(x)f (x)
[f (x)]2
= limx(x)kh(x)(x)k2[k(k1)h(x)+2k(x)h(x)+(x)2h(x)]
(x)2k2[kh(x)+(x)h(x)]2
= k(k1)[h()]2
k2[h()]2= k1
k< 1.
, .
k = 2
g(x) = x 2 f(x)f (x)
g(x) =2f(x)f (x) [f (x)]2
[f (x)]2.
L Hospital
g() = 0.
,
k,
xn+1 = xn k f(xn)f (xn)
, n = 0, 1, 2, . . . (2.32)
x0. ,
. -
(x)
(x) =f(x)
f (x). (2.33)
47
-
k 1,
f(x) = (x )kh(x) h() 6= 0
(x) =(x )kh(x)
k(x )k1h(x) + (x )kh(x) =(x )h(x)
kh(x) + (x )h(x) , 1. Newton-Raphson (x),
g(x) = x (x)(x)
= xf(x)f (x)
[f (x)]2[f(x)][f (x)][f (x)]2
g(x) = x f(x)f(x)
[f (x)]2 f(x)f (x) . (2.34)
g(x) ,
xn+1 = g(xn), n = 0, 1, 2, . . . (2.35)
. -
f (x) .
Newton-Raphson x0 [a, b]. .
2.5.4. ( ).
1. f(x) C2[a, b]2. f(a)f(b) < 0
3. f (x) 6= 0, x [a, b]4. f (x) [a, b]
5. | f(c)f (c)
| b a, c [a, b] |f (x)|
48
-
x0 [a, b] Newton-Raphson - f(x) [a, b].
(2)
f(x) [a, b]. (3) f(x) - (f > 0) (f < 0) [a, b]. [a, b] f(x). (4) f(x) (f (x) 0) (f (x) 0). (5), -
.
y
x{f( )
x2 x1 x0
M0
P0
y=f(x)
f(b)
b
}
2.9: Newton-Rapshon
2.9
tan = f (x0) =M0P0x0 x1 =
f(x0)
x0 x1
x0 x1 = f(x0)f (x0)
x1 = x0 f(x0)f (x0)
x0 Ox Newton-Raphson.
(5) : -
x0 [a, b], x1 [a, b].
49
-
x0 a b, x1 [a, b].
f(x) = x3 2x 1, x [1, 2].
Newton-Raphson -
.
2.5.4 -
f(x) C2[1, 2] f(1)f(2) < 0. f (x) = 3x22 6= 0 f (x) = 6x > 0 x [1, 2]. , 5) - |f(1)/f (1)| = 2 > 1, Newton-Raphson [1, 2]. [3
2, 2],
f(32)f(2) < 0
f(32)/f (3
2) = 5
30< 1. Newton-
Raphson x0 [32 , 2].
1. f(x) = x2 c, x > 0, c > 0 . NR
c x0 > 0.
[a, b] 0 < a 0. NR
xn+1 = xn x2n c2xn
50
-
xn+1 =1
2(xn +
c
xn), n = 0, 1, 2, ...
.
2. 1/c . c > 0, NR 1/c.
1/c
f(x) =1
x c = 0
NR
xn+1 = xn 1xn c
1x2n
xn+1 = xn(2 cxn), n = 0, 1, 2, ... (2.36) (2.36)
.
f (x) = 1x2
< 0, f (x) =2
x3> 0
x > 0 4.8 [a, b] 0 < a < c1 < b
f(b)
f (b)= b(bc 1) b a
b1 b b2,
b1,2 =11 ac
c
x > 0 0 < b < 2c1. NR x0
0 < x0 < 2c1 (2.37)
51
-
3. NR - e1. c = e (2.37) 0 < x0 < 2e1 0.735776 x0 = 0.3 (2.36) :
x0 = 0.3 2 ex0 = 1.1845157x1 = 0.355355 2 ex1 = 1.0340461x2 = 0.36745345 2 ex2 = 1.00111583x3 = 0.36787907 2 ex3 = 1.0000014x4 = 0.36787958 2 ex4 = 1.0000000
, .
4. f(x) C1[a, b], f (x) 6= 0 x [a, b] f(x) = 0 [a, b]. g(x) = x + h(x)f(x), h(x) .
g(x) = g(). -
g() = 0.
g(x) = 1 + h(x)f(x) + h(x)f (x)
x =
g() = 0 = 1 + h()f ()
f() = 0.
h() = 1f ()
h(x) ( )
h(x) = 1f (x)
.
xn+1 = g(xn)
xn+1 = xn f(xn)f (xn)
, n = 0, 1, 2, ...
52
-
Newton-Raphson.
5. f(x) = xk c, x > 0, c > 0 k , NR k
c
x0 > 0.
2.5.4
[a, b] 0 < a < kc b ,
b > 1k[(1 k)a+ c/ak1].
NR
xn+1 = xn xkn ckxk1n
xn+1 = (1 1k)xn +
1
kcx1kn , n = 0, 1, 2, ...
k = 2
xn+1 =1
2(xn + c/xn).
17 x0 = 4
:
x1 = 4, 12x2 = 4, 123 106x3 = 4, 123 1056 2561 77x4 = 4.123 1056 2561 7660 5498 2140 9856
x4 28 . -
.
-
. -
(100 ..-100 ..)
53
-
2.5.2 Newton 2
Bailey
, Newton 2 -
( )
. -
( 2 ).
f(x) = 0.
f(x) Taylor x = xn
f (xn+1) = f (xn) + hf (xn) +
h2
2!f (xn) +
h3
3!f (xn) + . . .
xn+1 = xn + h.
f (xn) = 0 ,
f (xn) + h
[f (xn) +
hf (xn)2
]= 0.
h , h, h = f (xn) /f (xn)(. Newton-1 ) ,
f (xn) + h
[f (xn) f (xn) f
(xn)2f (xn)
]= 0
h
h = f (xn)f (xn)
(f (xn)f(xn)
2f (xn)
) .
xn+1 = xn + h
xn+1 = xn f (xn)f (xn) f (xn)f(xn)2f (xn)
, n = 0, 1, 2, . . . (2.38)
Newton 2 .
54
-
2.6
Newton -
,
x0 - f (xn). f(x) ,
. -
Newton-Raphson.
.
-
.
Newton-Raphson f (xn)
f (xn) f (xn1)xn xn1
.
y
x
x0=bx2x1 x3x-1 =
2.10: .
55
-
f(x) C[a, b] x1, x0 [a, b]. n = 0, 1, 2, . . . xn+1
xn+1 = xn f(xn)(xn xn1)f(xn) f(xn1) =
f(xn)xn1 f(xn1)f(xn)f(xn) f(xn1)
(2.39)
f(xn) 6= f(xn1). ,
f(a)f(b) > 0, .
f (x) , 6= xn1 6= xn n = x xn. (2.39) :
n+1 = xn+1 = f(xn)n1 f(xn1)nf(xn) f(xn1) =
=f(xn)n1 f(xn1)n
xn1 xn xn1 xn
f(xn) f(xn1) .(2.40)
f(xn)n1 f(xn1)nxn1 xn = nn1
f(xn)n
f(xn1)n1
xn1 xn =
= nn1
f(xn)f()xn
f(xn1)f()xn1
xn xn1= nn1f [xn, , xn1] (2.41)
f [xn, , xn1] =f(xn)f()
xn f(xn1)f()
xn1xn xn1 . (2.42)
G(x) = f(x)f()x , -
f [xn, , xn1] =G(xn)G(xn1)
xn xn1 = G(n). (2.43)
56
-
G(x) =f (x)(x ) + f() f(x)
(x )2 (2.44)
Taylor f (x)
f() = f(x) + f (x)( x) + f()2
( x)2. (2.45)
(2.44) (2.45)
G(x) =f ()2
(2.43)
f [xn, , xn1] = G(n) =
f ()2
. (2.46)
, (2.44), (2.42), (2.43), (2.46)
n+1 = nn1f [xn, , xn1](xn1 xn)
f(xn) f(xn1)= nn1
(f (n)
2
)( 1f (n)
), (2.47)
n n xn1, xn . (2.47) -
.
2.6.1. f() = 0, f () 6= 0 f (x) , x1, x0 I = [ , + ], > 0.
. Ma f (x)f (x)
x x [ a, + a]. f (x) f (x) f () 6= 0, > 0,
f (x)f (x) M x x [ , + ]. > 0
57
-
M = K < 1, < M M. |x1 | |x0 | , |1| |10|M 2M = K < .
, |2| |01|M = |1|(|0|M) < (K)(M) < K2. i < K
i i1 < Ki1, - |i+1| < Ki+1 < , xi+1 I i. limi i = 0 I.
-
m > 0 n+1 = Kmn .
n = Kmn1 n1 = K
1m
1mn . ,
(2.47)
n+1 = Mnn1 = Mn(K1m
1mn ) Kmn (2.48)
1 +1
m= m (2.49)
m =15
2(2.50)
n+1 = Kmn m = 1.618.
2.7 - -
Aitken
Aitken.
{xn}, n = 0, 1, 2, . . . :
n+1n
= k, n = 0, 1, 2, . . . (2.51)
n = xn , |k| < 1. - xn, xn+1, xn+2 ., (2.51) :
xn+1 xn =
xn+2 xn+1
58
-
=xnxn+2 x2n+1
xn+2 2xn+1 + xn = xn (xn+1 xn)2
xn+2 2xn+1 + xn (2.52)
= xn (xn)2
2xn(2.53)
xn = xn+1xn 2xn = xn+1xn = xn+22xn+1+xn. {xn} n = 0, 1, 2, . . . ,
{xn} n = 0, 1, 2, . . . (2.53)
xn = xn (xn)
2
2xn, n = 0, 1, 2, . . . (2.54)
Aitken. -
limn
xn xn = 0
limn
xn+1 xn = k < 1
.
,
Aitken, .
2.8
p(x) = anxn + an1xn1 + a1x+ a0 = 0
p(x) n (an 6= 0) , -
.
59
-
.
, -
.
.
2.8.1. p(x) n 1, p(x) = 0 .
.
2.8.1. p(x) n 1, 1, 2, . . . , k m1, m2, . . . , mk
ki=0mi p(x) =
an(x 1)m1(x 2)m2 (x k)mk .
i 1 (m1 =m2 = mk = 1), n n.
2.8.2. p(x) q(x) n. 1, 2, . . . , k, k > n p(i) = q(i) i = 1, 2, . . . k, p(x) = q(x) x.
2.8.3. p(x) n, q(x) p(x) (x )q(x) + p(). n 1, q(x) n 1, q(x) 0. 2.8.2. p(x) n 1 , n 1 p(x) = (x )q(x). 2.8.4. p(x) n 1. p(x) m p() = p() = = pm1() = 0 p(m)() 6= 0.
-
p(x), q(x) 2.8.2.
2.8.5. p(x) n 1 p(x). q(x) n1 p(x) = (x )q(x) (. 2.8.2 ), :
60
-
) m q(x) m 1. ( m = 1, q(x)).
) 6= , p(x) q(x).
2.8.1 Horner
p(x) = anxn+an1xn1+ a1x+a0.
:
) xk, k = 2(1)n, n 1 -,
) akxk, k = 1(1)n, n ,
) n
k=0 akxk, n .
2n 1 n . p(x) = anx
n + an1xn1 + a1x+ a0, an 6= 0 (2.55) p(x0) x0,
p(x) (x x0)q(x) + r. (2.56)
p(x0) = r. (2.57)
q(x) = nxn1 + n1xn2 + + 2x+ 1, (2.58)
p(x) = anxn + an1xn1 + a1x+ a0
(x x0)(nxn1 + n1xn2 + + 2x+ 1) + r= nx
n + n1xn1 + + 2x2 + 1x(nx0xn1 + n1x0xn2 + + 2x0x+ 1x0) + r
= nxn + (n1 nx0)xn1 + + (1 2x0)x+ r 1x0
(2.59)
61
-
an = n
an1 = n1 nx0... (2.60)
a1 = 1 2x0a0 = r 1x0
n = an
n1 = an1 + nx0... (2.61)
1 = a1 + 2x0
r = a0 + 1x0
i = ai + i+1x0, i = n(1)0 (2.62)
n+1 = 0 0 = r = p(x0), n n p(x0). i :
an an1 an2 a1 a0x0 bnx0 bn1x0 b2x0 b1x0
bn bn1 bn2 b1 b0 = p(x0)
Horner p(x)
p(x) = (. . . ((
n1 anx0 + an1)x0 + an2
n2
)x0 + + a1)x0 + a0 (2.63)
62
-
2.8.2
p(x)
Horner -
p(x). ,
p(x) = (x x0)q(x) + r (2.64)
p(x) = q(x) + (x x0)q(x) (2.65)
p(x0) = q(x0) (2.66)
p(x0) Horner,
q(x) q(x) x x0. p(k)(x) k + 1 Horner., Horner :
p(x) = (x x0)q1(x) + r0q1(x) = (x x0)q2(x) + r1
... (2.67)
qn1(x) = (x x0)qn(x) + rn1qn(x) = (x x0) 0 + rn.
p(x) = (x x0)q1(x) + r0= (x x0)[(x x0)q2(x) + r1] + r0 (2.68)= (x x0)2q2(x) + (x x0)r1 + r0
p(x)
p(x) = rn(xx0)n+ rn1(xx0)n1+ + r1(xx0)+ r0. (2.69)
63
-
p(x) Taylor x0
p(x) = p(x0)+(x x0)
1!p(x0)+
(x x0)22!
p(x0)+ +(x x0)n
n!p(n)(x0).
(2.70)
p(x)
p(k)(x0) = k!rk, k = 0(1)n (2.71)
rk = qk(x0), k = 0(1)n. (2.72)
Horner
p(x) x = x0 .. p(x)
an an1 a2 a1 a0x0 nx0 3x0 2x0 1x0
n n1 2 1 0 = r0x0 nx0 3x0 2x0
n n1 2 1 = r1x0 nx0 3x0
n n1 2 = r2 p(x0) = 2!
2
1. p(x) = 6x4 53x3 + 184x2 295x +186. Horner p(2), p(2), p(2), p(2), p(4)(2).
6 -53 184 -295 186
2 12 -82 204 -182
6 -41 102 -91 4 = r02 12 -58 88
6 -29 44 3 = r12 12 -34
6 -17 10 = r22 12
6 = r4 5 = r3
64
-
p(k)(x0) = k!rk k = 0(1)4 :
p(2) = 0!r0 = 1 4 = 4p(2) = 1!r1 = 1 (3) = 3p(2) = 2!r2 = 2 10 = 20p(2) = 3!r3 = 6 (5) = 30p(4)(2) = 4!r4 = 24 6 = 144
2. Horner -
p(x) = 3x2 4x + 5 p(x) = a + (x 2) + (x 2)2.
Taylor x0 = 2 :
p(x) = p(2) +(x 2)
1!p(2) +
(x 2)22!
p(2),
rk =p(k)(x0)
k!, k = 0, 1, 2,
p(x) = r0 + r1(x 2) + r2(x 2)2.
r0, r1, r2, Horner :
3 -4 5
2 6 4
3 2 9 = r02 6
3 = r2 8 = r1
p(x) = 9 + 8(x 2) + 3(x 2)2.
65
-
3
3.1 Gauss
-
.
-
. 20 Gramer ,
2 ,
2
! -
,
. -
Gauss.
a(1)11 x1 + a
(1)12 x2 + a
(1)13 x3 + . . .+ a
(1)1nxn = b
(1)1
a(1)21 x1 + a
(1)22 x2 + a
(1)23 x3 + . . .+ a
(1)2nxn = b
(1)2
a(1)31 x1 + a
(1)32 x2 + a
(1)33 x3 + . . .+ a
(1)3nxn = b
(1)3
a(1)n1 x1 + a
(1)n2x2 + a
(1)n3x3 + . . .+ a
(1)nnxn = b
(1)n
(3.1)
66
-
a(1)11 a
(1)12 a
(1)13 a(1)1n
a(1)21 a
(1)22 a
(1)23 a(1)2n
a(1)31 a
(1)32 a
(1)33 a(1)3n
......
......
a(1)n1 a
(1)n2 a
(1)n3 a(1)nn
x1x2x3...
xn
=
b(1)1
b(1)2
b(1)3...
b(1)n
(3.2)
A(1)x = b(1). (3.3)
detA(1) 6= 0 . b(1) 6= . (3.1)
, (3.1).
a(1)11 x1 + a
(1)12 x2 + a
(1)13 x3 + . . .+ a
(1)1n xn = b
(1)1
a(2)22 x2 + a
(2)23 x3 + . . .+ a
(2)2n xn = b
(2)2
a(2)32 x2 + a
(2)33 x3 + . . .+ a
(2)3n xn = b
(2)3
...a(2)n2 x2 + a
(2)n3x3 + . . .+ a
(2)nnxn = b
(2)n
(3.4)
(3.1) x1 . (3.4)
a(1)11 a
(1)12 a
(1)13 . . . a
(1)1n
a(2)22 a
(2)23 . . . a
(2)2n
0 a(2)32 a(2)33 . . . a(2)3n...
... ...a(2)n2 a
(2)n3 . . . a
(2)nn
x1x2x3...
xn
=
b(1)1
b(2)2
b(2)3...
b(2)n
A(2)x = b(2).
(.(3.4) )
67
-
x2.
a(1)11 x1 + a
(1)12 x2 + a
(1)13 x3 + . . .+ a
(1)1nxn = b
(1)1
a(2)22 x2 + a
(2)23 x3 + . . .+ a
(2)2nxn = b
(2)2
a(3)33 x3 + . . .+ a
(3)3nxn = b
(3)3
... ...a(3)n3 x3 + . . .+ a
(3)nnxn = b
(3)n
a(1)11 a
(1)12 a
(1)13 . . . a
(1)1n
a(2)22 a
(2)23 . . . a
(2)2n
a(3)33 . . . a
(3)3n
0... ...
a(3)n3 . . . a
(3)nn
x1x2x3...
xn
=
b(1)1
b(2)2
b(3)3...
b(3)n
A(3)x = b(3).
r 1
a(1)11 x1 + a
(1)12 x2 + . . . + a
(1)1,r1xr1 + a
(1)1,rxr + . . . + a
(1)1nxn = b
(1)1
a(2)22 x2 + . . . + a
(2)2,r1xr1 + a
(2)2,rxr + . . . + a
(2)2nxn = b
(2)2
. . . . . . . . . . . . . . ....
a(r1)r1,r1xr1 + a
(r1)r1,rxr + . . . + a
(r1)r1,nxn = b
(r1)r1
a(r)r,rxr + . . . + a
(r)rn xn = b
(r1)r
. . . . . . . . ....
a(r)n,rxr + . . . + a
(r)nnxn = b
(r)n
a(1)11 a
(1)12 . . . a
(1)1,r1 a
(1)1r . . . a
(1)1n
a(2)22 . . . a
(2)2,r1 a
(2)2r . . . a
(2)2n
0 . . . ... ... . . . ...a(r1)r1,r1 a
(r1)r1,r . . . a
(r1)r1,n
a(r)rr . . . a
(r)rn
0 ... . . . ...a(r)nr . . . a
(r)nn
x1x2...
xr1xr...
xn
=
b(1)1
b(2)2...
b(r1)r1b(r)r
...
b(r)n
68
-
A(r)x = b(r).
, n 1 -
a(1)11 x1 + a
(1)12 x2 + . . .+ a
(1)1,r1xr1 + a
(1)1,rxr + . . .+ a
(1)1nxn = b
(1)1
a(2)22 x2 . . .+ a
(2)2,r1xr1 + a
(2)2,rxr + . . .+ a
(2)2nxn = b
(2)2
...a(n1)n1,n1xn1 + a
(n1)n1,nxn = b
(n1)n1
a(n)nnxn = b
(n)n
(3.5)
A(n)x = b(n), (3.6)
A(n) . (3.5)
xn =b(n)n
a(n)nn
xi =b(i)i
nj=i+1 a
(i)ij xj
a(i)ii
, i = n 1(1)1. (3.7)
Gauss
{A(k)
}, k = 1(1)n, A(1) = A
{b(k)}, k = 1(1)n
A(n) U .
x1 n1 .
a(1)ij = aijb(1)i = bi
, i = 1(1)n, j = 1(1)n,
x1 i- (3.1) i = 2(1)n, mi1 ,
69
-
, i- ,
mi1 = a(1)i1
a(1)11
, i = 2(1)n (3.8)
a(1)11 6= 0. a(1)11 .
[a(1)i2 +mi1a
(1)12
]x2 + . . .+
[a(1)in +mi1a
(1)1n
]xn = b
(1)1 +mi1b
(1)1
a(2)i2 x2 + . . .+ a
(2)in xn = b
(2)i , i = 2(1)n
a(2)ij = a
(1)ij +mi1a
(1)1j , i = 2(1)n, j = 2(1)n (3.9)
b(2)i = b
(1)i +mi1b
(1)1 , i = 2(1)n.
x1 i-
a(2)i1 = a
(1)i1 +mi1a
(1)11 = 0.
, n 1
a(2)22 x2 + . . .+ a
(2)2nxn = b
(2)2
......
...
a(2)n2 x2 + . . .+ a
(2)nnxn = b
(2)n .
a(2)22 6= 0, mi2
x2 n2 ... (3.6). -
M (1)
M (1) =
1 0m21m31 In1...
mn1
(3.10)
70
-
Gauss -
M (1). :
M (1)A(1)x = M (1)b(1) (3.11)
A(2)x = b(2) (3.12)
A(2) = M (1)A(1) b(2) = M (1)b(1).
3.1.1. A(1)x = b(1) A(2)x = b(2).
. (3.1) ,
detA(1) 6= 0. (3.11) (3.12)
A(2) = M (1)A(1)
detA(2) =[detM (1)
] [detA(1)
]= detA(1) 6= 0
detM (1) = 1. A(2) (3.4) . (3.11)
(3.1) (3.4), (3.1)
(3.4) .
r1 , a(r)rr 6= 0,
a(r)rr xr + . . .+ a(r)rnxn = b
(r)r .
xr n r mir i- i =r + 1(1)n.
mir = a(r)ir
a(r)rr
, i = r + 1(1)n
[a(r)i,r+1 +mira
(r)r,r+1
]xr+1+. . .+
[a(r)in +mira
(r)rn
]xn =
[b(r)i +mirb
(r)r
]71
-
a(r+1)i,r+1xr+1 + . . .+ a
(r+1)in xn = b
(r+1)i , i = r + 1(1)n
a(r+1)ij = a
(r)ij +mira
(r)rj , i = r + 1(1)n, j = r + 1(1)n (3.13)
b(r+1)i = b
(r)i +mirb
(r)r , i = r + 1(1)n.
A(r+1)x = b(r+1). (3.14)
M (r) =
Ir1 0 00 1
mr+1,r 1 0... mr+2,r 0 1
.... . .
0 mn,r 0 1
(3.15)
r
M (r)A(r)x = M (r)b(n)
A(r+1)x = b(r+1).
-
-
M = M (n1) . . .M (2)M (1). (3.16)
MA(1)x = Mb(1) (3.17)
A(n)x = b(n). (3.18)
3.1.2. A(n)x = b(n) A(1)x = b(1).
. 3.1.1
.
72
-
3.1.1 Axk = bk, k = 1(1)
Axk = bk, k = 1(1), (3.19)
xk = [x1k, x2k, . . . , xnk]T
bk = [b1k, b2k, . . . , bnk]T
AX = B
X B n . detA 6= 0, Gauss
b B.
3.1.2 A1
AX = I
(3.19).
3.1.3 detA
A(n)
A(n) = MA(1) (3.20)
detA(n) = [detM ][detA(1)
].
(3.16)
detM =
n1r=1
detM (r)
73
-
M (r), r = 1(1)n 1
detM = 1 (3.21)
A(n)
detA(1) = detA(n) = a(1)11 a
(2)22 . . . a
(n)nn (3.22)
Gauss.
3.1.4 Gauss
Gauss Ax = b.
1. A = (aij) , b = (bi)
2. i = 1(1)n ai,n+1 = bi
3. r = 1(1)n 1 3.1-3.33.1 p ap,r 6= 0, p =
r(1)n. p ( - ). .
3.2 p 6= r ( p r ). q = r(1)n
bq = arqarq = apqapq = bq
3.3 i = r + 1(1)n 3.3.1-3.3.2
3.3.1
mir = airarr
3.3.2 j = r + 1(1)n+ 1
aij = aij +mirarj
74
-
4. ann = 0 . - .
5. ( )
xn = an,n+1/ann
6. i = n 1(1)1
xi =
[ai,n+1
nj=i+1 aijxj
]aii
7. xi, i = 1(1)n. .
3.1.5
Gauss
,
Gauss .
r- -
, , a(r)ir .
i r .
-
.
a(r)ir ;
3.1.3. A(1) ,
a(r)ir .
. -
3.1.1 detA(r) = detA(1) detA(r) 6= 0.
detA(1) = det
a(1)11 a
(1)12 a(1)1n
0 a(2)22 a(2)2n
......
...
0 a(2)n2 a(2)nn
= a(1)11 det
a
(2)22 a(2)2n...
...
a(2)n2 a(2)nn
= a(1)11 detA
(2)n1
75
-
detA(r) =[a(1)11 a
(2)22 . . . a
(r1)r1,r1
]detA
(r)nr+1,
A(r)nr+1 =
a
(r)rr a(r)rn...
...
a(r)nr a(n)nn
.
detA(r)nr+1 6= 0 Anr+1
.
6= 0 A(r)nr+1.
a(r)rr = 0, r
, , a(r)ir 6= 0 (. 3.1.3).
r i . - A(r) (r) A(r) b(r), .
A(r)x = (r) (3.23)
(r < i)
r i
Iri =
r
i
1 | |. . . | 0 | 0
1 | | 0 1
| 1 |0 | . . . | 0
| 1 | 1 0
| | 10 | 0 | . . .
| | 1
,
(3.24)
76
-
-
I2ri = I. (3.25)
r (3.23) Iri - M (r). [
M (r)Iri]A(r)x =
[M (r)Iri
](r) (3.26)
A(r+1)x = (r+1). (3.27)
i = r Iri = Irr = I.
A(1)x = (1) (3.28)
M = [M (n1)In1,in1] [M (n2)In2,in2] . . . [M (2)I2,i2] [M (1)I1,i1](3.29)
MA(1)x =M(1) (3.30)
A(n)x = (n). (3.31)
-
(3.31) (3.28).
3.1.4. A(1)x = (1) A(n)x = (n).. detA(1) 6= 0. (3.30) (3.31)
A(n) =MA(1) (3.32)
77
-
detA(n) = [detM] [detA(1)] . (3.33) detA(n) 6= 0 detM 6= 0. (3.29)
detM =[n1r=1
detM (r)
][n1r=1
det Ir,ir
](3.34)
M (r), r = 1(1)n 1
n1r=1
detM (r) = 1. (3.35)
n1r=1
det Ir,ir 6= 0 (3.36)
r = 1(1)n 1 r 6= irdet Ir,ir = 1
det Ir,ir I - r i ( r = ir, det Irr = 1). (3.34), (3.35) (3.36)
detA(n) 6= 0
(3.31) .
(3.28)
x =[A(1)
]1(1)
(3.31) (3.30),
A(n)x =MA(1){[A(1)]1 (1)} =M(1) = (n)
(3.28) (3.31)
.
78
-
3.1.6
Gauss -
. -
, ,
-
, .
-
,
Gauss
.
.
.
a(r)rr
a(r)rr (r < i). a
(r)rr , -
mir -
,
. Wilkinson
.
-
. -
r A(r) r , |mir| 1, :
a(r)pr = maxi
a(r)ir , r i n r p A(r) r-. - r
79
-
n r + 1 A(r)
a(r)pr = maxij
a(r)ij , r i, j n p r . ,
= 103. -
,
.
x1 + 2x2 x3 = 02x1 x2 = 1x1 + 7x2 3x3 = 5
-
Gauss i) ii) .
(i) [A...b],
1 2 1 02 1 0 1
1 7 3 5
Gauss
. -
21
1 2 1 02 1 0 1
1 7 3 5
3
1 2 1 00 3 2 1
0 9 4 5
1
80
-
1 2 1 00 3 2 1
0 0 2 2
2
x1 + 2x2 x3 = 03x2 2x3 = 1
2x3 = 2
x3 = 1, x2 = 1 x1 = 1.
(ii) Gauss -
. 1 2 1 02 1 0 1
1 7 3 5
(1)(2)
(3)
1/21/2
2 1 0 11 2 1 0
1 7 3 5
(2)(1)
(3)
2 1 0 10 3/2 1 1/2
0 15/2 3 9/2
(2)(1)
(3)1
1/5
2 1 0 10 15/2 3 9/2
0 3/2 1 1/2
(2)(3)
(1)
2 1 0 10 15/2 3 9/2
0 0 2/5 2/5
(2)(3)
(1)2
2x1 x2 = 1152x2 3x3 = 92
25x3 = 25
81
-
x3 = 1, x2 = 1 x1 = 1.
3.1.7 Gauss -
Gauss
1. A = (aij), b = (bi) n.
2. i = 1(1)n ai,n+1 = bi.
3. i = 1(1)n
h(i)= i
4. r = 1(1)n 1 4.1-4.4 (- ).
4.1. p
r p n
|a(h(p),r)| = maxrjn
|a(h(j),r)|
4.2. a(h(p), r) = 0 ( ). .
4.3. h(r) 6=h(p) ( h(p) h(r))
q = h(r)h(r) = h(p)h(p) = q
( ).
4.4. i = r + 1(1)n i ii
i.
m(h(i),r) = a(h(i),r)a(h(r),r)
82
-
ii. j = r + 1(1)n+ 1
a(h(i),j) = a(h(i),j)+m(h(i),r)a(h(r),j)
a(h(n),n) = 0 ( ). .
5. ( )
xn = a(h(n),n+ 1)/a(h(n),n)
6. i = n 1(1)1
xi =a(h(i),n+ 1)nj=i+1 a(h(i),j)xj
a(h(i),i)
7. xi, i = 1(1)n. .
-
,
.
30, 00x1 + 591.400x2 = 591.7005, 291 6, 130x2 = 46, 78.
-
m21 =5, 291
30, 00= 0, 1764
30, 00x1 + 591.400x2 = 591.700 104.300x2 = 104.400
x2 = 1, 001 x1 = 10, 00.
x1 = 10, 00 x2 = 1, 000. ,
83
-
(scaled)
.
.
.
30, 00
591.400= 0, 00005073
5, 291
6, 130= 0, 8631
-
.
3-4.1,
:
3. i = 1(1)n 3.1-3.3
3.1. si = max1jn |aij |3.2. si = 0
3.3. h(i) = i
4. r = 1(1)n 1 4.1-4.44.1. p r p n
|a(h(p),r)|s(h(p))
= maxrjn
|a(h(j),r)|s(h(j))
.
-
Ax = b D1 i- (si)
1.
3.2 Jordan
Jor-
dan
.
Gauss
xi .
84
-
(3.1), -
Jordan
Gauss, (3.4) :
a(1)11 x1 + a
(1)12 x2 + a
(1)13 x3 + . . . + a
(1)1n xn = b
(1)1
a(2)22 x2 + a
(2)23 x3 + . . . + a
(2)2n xn = b
(2)2
a(2)32 x2 + a
(2)33 x3 + . . . + a
(2)3n xn = b
(2)3
...
a(2)n2 x2 + a
(2)n3 x3 + . . . + a
(2)nnxn = b
(2)n
(3.37)
x1 n1
A(2)x = b(2).
Jordan
x2 n 2 , .
a(1)11 x1 a
(3)13 x3 + . . . + a
(3)1nxn = b
(3)1
a(2)22 x2 + a
(3)23 x3 + . . . + a
(3)2nxn = b
(3)2
a(3)33 x3 + . . . + a
(3)3nxn = b
(3)3
...
a(3)n3x3 + . . . + a
(3)nnxn = b
(3)n
(3.38)
A(3)x = b(3) (3.39)
. r 1
a(1)11 x1 +a
(r)1r xr + . . .+ a
(r)1nxn = b
(r)1
a(2)22 x2 +a
(r)2r xr + . . .+ a
(r)2nxn = b
(r)2
. . ....
a(r1)r1,r1xr1 +a
(r)r1,rxr . . .+ a
(r)r1,nxn = b
(r)r1
a(r)rr xr + . . .+ a
(r)rnxn = b
(r)r
...
a(r)nr xr + . . .+ a
(r)nnxn = b
(r)n
(3.40)
85
-
A(r)x = b(r)
r 1 . , n :
a(1)11 x1 = b
(n+1)1
a(2)22 x2 = b
(n+1)2
. . ....
a(n)nnxn = b
(n+1)n
(3.41)
A(n)x = b(n+1) (3.42)
A(n) . (3.42)
xi =1
a(i)ii
b(n+1)i
a(i)ii 6= 0, i = 1(1)n.
a(1)ij = aij i, j = 1(1)n
b(1)i = bi i = 1(1)n
a(1)11 6= 0,
mi1 = a(1)i1
a(1)11
, i = 2(1)n.
x1 i- , - mi1 i-, - (3.37),
a(2)ij = a
(1)ij +mija
(1)1j , i = 1(1)n, i 6= 1
j = 2(1)n
b(2)i = b
(1)i +mi1b
(1)1 , i = 1(1)n, i 6= 1.
86
-
-
a(2)1j = a
(1)1j , j = 2(1)n
b(2)1 = b
(1)1 .
x2 n2 , (3.38)
a(3)ij = a
(2)ij +mi2a
(2)2j , i = 1(1)n, i 6= 2, j = 3(1)n
b(3)i = b
(2)i +mi2b
(2)2 , i = 1(1)n, i 6= 2
mi2 = a(2)i2
a(2)22
, i = 1(1)n, i 6= 2.
a(3)2j = a
(2)2j , j = 3(1)n
b(3)2 = b
(2)2 .
(3.41). -
A - n n . Jordan
n n M MAx = Mb (3.43)
MA = I. (3.44)
M = A1 (3.45)
x = Mb. (3.46)
A(1)x = b(1) (3.47)
87
-
M (1) -
M (1) =
11 02131 In1...
n1
(3.48)
i1 =
{1/a
(1)11 , i = 1
a(1)i1 /a(1)11 , i 6= 1 a
(1)11 6= 0. (3.49)
Jordan
(3.47) M (1), :
M (1)A(1)x = M (1)b (3.50)
A(2)x = b(2). (3.51)
r :
M (r)A(r)x = M (r)b (3.52)
M (r) =
1r
Ir1... 0
r1,r0 0 rr 0 0
r+1,r
0 ... Inrnr
(3.53)
ir
i1 =
{1/a
(r)rr , i = r
a(r)ir /a(r)rr , i 6= r, a(r)rr 6= 0, r = 1(1)n.
(3.52)
A(r+1)x = b(r+1) (3.54)
88
-
A(r+1) =
[Ir 0
](3.55)
. -
M = M (n)M (n1) . . .M (2)M (1) (3.56)
M (1) M (i), i = 2(1)n 1 (3.48) (3.53),
M (n) =
1,n
In1...
n1,n0 0 nn
. (3.57)
MA(1)x = Mb(1)
x = Mb(1). (3.58)
Gauss, -
Jordan
. ( -
).
Gauss -
. Jordan
.
Jordan -
.
89
-
1 2 1 02 1 0 1
1 7 3 5
(1)(2)
(3)
1/21/2
2 1 0 11 2 1 0
1 7 3 5
(2)(1)
(3)
2 1 0 10 3/2 1 1/2
0 15/2 3 9/2
(2)(1)
(3)1
2/15
1/5
2 1 0 10 15/2 3 9/2
0 3/2 1 1/2
(2)(3)
(1)
115/2
2 0 2/5 8/50 15/2 3 9/2
0 0 2/5 2/5
(2)(3)
(1)2
2 0 0 20 15/2 0 15/2
0 0 2/5 2/5
(2)(3)
(1)3
x1 = 1, x2 = 1 x3 = 1.
3.2.1 Jordan -
Jordan
Ax = b :
1. A = (aij) , b = (bi) n.
2. i = 1(1)n
ai,n+1 = bi
90
-
3. i = 1(1)n
h(i)= i
4. r = 1(1)n 4.1-4.4 ().
4.1. p
r p n
|a(h(p), r))| = maxrjn
|a(h(j), r)|
4.2. a(h(p),r)= 0 -. .
4.3. h(r) 6=h(p)
q=h(r)h(r)=h(p)h(p)=q
( )
4.4. i = 1(1)n i 6= r i ii
i.
m(h(i),r) = a(h(i),r)a(h(r),r)
ii. j = r + 1(1)n+ 1
a(h(i),j) = a(h(i),j)+m(h(i),r)a(h(r),j)
5. i = 1(1)n
a(h(i),i) = 0 . .
xi = a(h(i),n + 1)/a(h(i),i)
6. xi, i = 1(1)n.
91
-
3.2.2
-
, ,
Gauss Jordan.
k Gauss :
n k
a11 a12 a13 a1k a1,k+1 a1na22 a23 a2k a2,k+1 a2n
a33 a3k a3,k+1 a3n0
. . ....
......
akk ak,k+1 aknak+1,k ak+1,k+1 ak+1,n
0...
......
ank an,k+1 ann
x(1)1 x
(2)1 x()1
x(1)2 x
(2)2 x()2
x(1)3 x
(2)3 x()3
......
...
x(1)k x
(2)k x()k
x(1)k+1 x
(2)k+1 x()k+1
......
...
x(1)n x
(2)n x()n
=
nk
l
n k
=
b(1)1 b
(2)1 b()1
b(1)2 b
(2)2 b()2
b(1)3 b
(2)3 b()3
......
...
b(1)k b
(2)k b()k
......
...
b(1)n b
(2)n b()n
(3.59)
l
- A. -
,
(nk) (nk+ ). (
k ). (n k)(n k+ ) - . n k - mik, i = k + 1(1)n n k . , -
n k + k A
92
-
. n k (n k)(n k + ) -. k = 1(1)n 1
n1k=1
(n k)
n1k=1
(n k)(n k + ) (3.60)
n1k=1
(n k)(n k + ) .
mk=1
k =m(m+ 1)
2
mk=1
k2 =m(m+ 1)(2m+ 1)
6
(3.60)
n(n 1)2
n(n 1)(2n 1 + 3)6
(3.61)
n(n 1)(2n 1 + 3)
6.
x(i)k , k = 1(1)n, i = 1(1) -
(3.7)
i n k aijxj , j = k + 1(1)n, n k k = 1(1)n 1, x(i)n - . x
(i)k
nk=1
1
93
-
n1k=1
(n k)
n1k=1
(n k)
n
n(n 1)2
(3.62)
n(n 1)
2.
(3.59) :
n(n 1 + 2)2
n(n 1)(2n 1 + 6)6
(3.63)
n(n 1)(2n 1 + 6)
6.
( = 1) Gauss
n2
2+n
2
n3
3+n2
2 5n
6 (3.64)
n3
3+n2
2 5n
6.
A1 Gauss ( = n)
3n2
2 n
2
4n3
3 3n
2
2 n
6 (3.65)
94
-
4n3
3 3n
2
2 n
6.
Gauss
O(n3/3) . -
(
) A1. Jordan
a11a22
. . .
a1k a1,k+1 a1n...
......
......
...
akk ak,k+1 aknak+1,k ak+1,k+1 ak+1,n
......
...
ank an,k+1 ann
X
=
B
nk
n 1 (n 1)(n k + ). -
Jordan.
(n 1)(n k + ) . A
nk=1
(n 1)
nk=1
(n 1)(n k + )
nk=1
(n 1)(n k + )
95
-
n(n 1) n(n 1)(n 1 + 2)
2
n(n 1)(n 1 + 2)2
.
n n . Jordan
n(n 1 + ) n(n 1)(n 1 + 2)
2 (3.66)
n(n 1)(n 1 + 2)2
.
-
( = 1)n2
n3
2 n
2 (3.67)
n3
2 n
2,
( = n)
2n2 n 3n3
2 2n2 + n
2 (3.68)
3n3
2 2n2 + n
2.
(3.67) -
Jordan
O(n3/2). Jordan Gauss
. -
Jordan .
96
-
A1 , -
. Jordan, ,
.
Gauss
.
Wilkinson.
Gauss
.
3.3 LU
-
Gauss , A(1)x = b(1)
MA(1)x = Mb(1)
A(n)x = b(n)
A(1) = M1A(n) (3.69)
(3.56)
M1 =[M (1)
]1 [M (2)
]1. . .[M (n1)
]1(3.70)
[M (r)
]1=
Ir1 01
mr+1,r 1 00 mr+2,r 0 1
......
. . .
mnr 0 0 1
. (3.71)
97
-
M1 =
1m21 1 0m31 m32 1m41 m42 m43 1
......
......
. . .
mn1 mn2 mn3 mn4 1
(3.72)
M1 . A(n) , (3.69) , -
A(n) A(1), A(1) -
M1 A(n). .
3.3.1. n n A = (aij) LU , L U ,
det [a11] 6= 0, det[a11 a12a21 a22
]6= 0, . . . , detA 6= 0.
,
L U .
. A
A = LU (3.73)
L ,
A =
121 1 031 32 1...
......
. . .
n1 n2 n3 1
u11 u12 u13 u1n
u22 u23 u2nu33 u3n
0. . .
...
unn
.(3.74)
98
-
, n2 - n2 . L ( - =1), n . -
L U . LU A
u11 = a11u12 = a12
...
u1n = a1n
(3.75)
A U -.
LU ,
21u11 = a2131u11 = a31
...
n1u11 = an1.
(3.76)
u11 = a11, a11 6= 0, (3.76) L. , r U r L, k = 1(1)r 1 U L, , .
1
21. . . 0
...
r1 1r+1,1 r+1,r 1...
......
. . .
n1 nr 1
u11 u1r u1,r+1 u1n. . .
......
...
ur1,r ur1,r+1 ur1,nurr ur,r+1 urn
0 . . ....
unn
99
-
r L r, r + 1, . . . , n U A,
r1j=1
rjujr + urr = arr
r1j=1
rjuj,r+1 + ur,r+1 = ar,r+1
r1j=1
rjujn + urn = arn.
urp, p = r(1)n
urp = arp r1j=1
rjujp, p = r(1)n. (3.77)
r U r + 1, r + 2, . . . , n L A
r1j=1
r+1,jujr + r+1,rurr = ar+1,r
r1j=1
r+2,jujr + r+2,rurr = ar+2,r
r1j=1
njujr + nrurr = anr.
pr, r + 1(1)n , urr 6= 0, r L
pr =1
urr
(apr
r1j=1
pjujr
), p = r + 1(1)n. (3.78)
100
-
, (3.77) p = r
urr = arr r1j=1
rjujr, r = 1(1)n
r = 2
u22 = a22 21u12= a22 a21a11a12
(= a
(2)22
)
u22 =1
a11det
[a11 a12a21 a22
].
a11 6= 0 det[a11 a12a21 a22
]6= 0
u22 6= 0. , urr 6= 0, r = 1(1)n.
.
L :
A(1) = LU
M1 = L A(n) = U.
Gauss
LU L - . Wilkinson ([1965] . 223)
-
,
-
, .
,
Gauss
. -
Gauss
-
n
j=1 ajbj
101
-
.
,
.
Gauss
, -
.
.
1. ,
-
, ,
. ,
,
|aii| >j 6=i
|aij | , i = 1(1)n. (3.79)
2. A
A = LU
Ax = b LUx = b (3.80)
Ly = b (3.81)
Ux = y. (3.82)
(3.81)
(ii = 1, i = 1(1)n)
y1 = b1
yi = bi i1j=1
ijyj , i = 2(1)n (3.83)
(3.82)
xn = yn/unn
102
-
xi =
(yi
nj=i+1
uijxj
)/uii, i = n 1(1)1.
3. LU L U , - -
Gauss. , L U A .
, A = (aij), n = 4u11 u12 u13 u1421 u22 u23 u2431 32 u33 u3441 42 43 44
.
, L -
Doolittle U Crout.
LU
A =
1 1 11 2 22 1 1
A = LU
1 1 11 2 22 1 1
=
1 0 02 21 1 0
314 32 1
u11 u1
12 u13
0 u3
22 u23
0 0 u5
33
103
-
u11 = 1 u12 = 1 u13 = 121u11 = 1 21 = 1/u11 = 131u11 = 2 31 = 2/u11 = 221u12 + u22 = 2 u22 = 2 21u12 = 121u13 + u23 = 2 u23 = 2 21u13 = 131u12 + 32u22 = 1 32 = (1 31u12)/u22 = 331u13 + 32u23 + u33 = 1 u33 = 1 31u13 32u23 = 2.
A =
1 0 01 1 02 3 1
1 1 10 1 1
0 0 2
.
LU
n n A LU .
1. : n, aij , i, j = 1(1)n A lii, i = 1(1)n L uii, i = 1(1)n U .
2. l11 u11 l11u11 =a11.
l11u11 = 0 ( ). -.
3. j = 2(1)n
u1j = a1j/l11( U)
lj1 = aj1/u11( L)
4. r = 2(1)n 1 4.1-4.2
4.1 lrr urr
104
-
lrr urr = arr r1j=1
lrj ujr
lrr urr = 0 ( ).
4.2 p = r + 1(1)n
urp =
(arp
r1j=1
lrj ujp
)/ lrr( r U)
lpr =
(apr
r1j=1
lpj ujr
)/ urr( r L)
5. unn lnn
unn lnn = ann r1j=1
lnj ujn
( lnn unn = 0, A = LU A )
6. (lij, j = 1(1)i, i = 1(1)n)
(uij, j = 1(1)n, i = 1(1)n)
.
L U . :
u11 u12 u13 . . . u1nl21 u22 u23 . . . u2nl31 l32 u33 . . . u3n...
......
...
ln1 ln2 ln3 . . . unn
105
-
-
, , , ...
,
u1j = a1j , j = 1(1)n.
r - ,
1
l21 1 0l31 l32 1...
.
.
....
. . .
.
.
....
.
.
.. . .
lr1 lr2 lr3 . . . lr,r1 1...
.
.
....
.
.
.. . .
ln1 ln2 ln3 . . . ln,r1 . . . ln,n1 1
u11 u12 . . . u1r . . . u1nu22 . . . u2r . . . u2n
0 . . ....
.
.
.
urr . . . urn
0 . . ....
unn
-
, r L
lr1u11 = ar1lr1u12 + lr2u22 = ar2lr1u13 + lr2u23 + lr3u33 = ar3
......
......
lr1u1r + lr2u2r + lr3u3r + . . . + lr,r1ur1,r1 = ar,r1
u11u12 u22 0u13 u23 u33...
......
. . .
u1,r1 u2,r1 u3,r1 . . . ur1,r1
lr1lr2lr3...
lr,r1
=
ar1ar2ar3...
ar,r1
r U
urp = arp r1j=1
lrj ujp, p = r(1)n.
106
-
L U .
1l21 1
l31 l32 1 0...
......
. . .
......
.... . .
lr1 lr2 lr3 . . . lr,r1 1lr+1,1 lr+1,2 lr+1,3 . . . lr+1,r1 lr+1,r1...
......
......
. . .
ln1 ln2 ln3 ln,r1 ln,r . . . 1
u11 u12 u1r u1nu22 u2r u2n
. . ....
......
urr urn0 . . .
...
unn
u1r = a1rl21u1r + u2r = a2r
......
...
lr1u1r + lr2u2r + . . . + lr,r1ur1,r + urr = arr
1
l21 1 0l31 l32 1...
. . ....
. . .
lr1 lr2 lr3 . . . lr,r1 1
u1ru2ru3r...
urr
=
a1ra2ra3r...
arr
r L
lpr =
(apr
r1j=1
lpj ujr
)/ urr, p = r + 1(1)n.
3.4 LU
LU A . A = LU LU A D L = LD U = D1U ,
107
-
A = LU = LDD1U = LU
LU LU A. - LU
.
:
A = LDU
LDU A L , D U .
3.4.1. A LDU A[r], r = 1(1)n 1
A[r] =
a11 . . . a1r... ...ar1 . . . arr
.
. A LDU - . A = L1D1U1 A =L2D2U2. A , D1 D2.
L1D1U1 = L2D2U2
L12 L1 = D2U2U11 D
11 (3.84)
(3.84) -
.
,
L12 L1 = I
108
-
L1 = L2.
U1 = U2.
L1 U1 , L1D1U1 =L2D2U2
D1 = D2.
A LDU - A[1] . . . A[n1] .
A = LDU LDU - A. L, D U . L U D L[k], D[k] U [k] . A[k] = L[k]D[k]U [k]
A[k] . , A[r], r = 1(1) 1 . 3.3.1 -
Gauss A = LA(n) L A(n) (3.72) (3.20), . A(n)
a(k)kk , k = 1(1)n
. D = diag (a(1)11 , a
(2)22 , . . . , a
(n)nn ) U = D1A(n),
A = LDU
LDU A.
LDU A
lij = mij , i = 2(1)n, j = 1(1)i 1dii = a
(i)ii , i = 1(1)n
uij =a(i)ij
a(i)ii
, i = 1(1)n, j = i+ 1(1)n.
109
-
LDU .
A = (LD)U = LU
l11 0l21 l
22
......
. . .
ln1 ln2 . . . l
nn
1 u11 . . . unn
1 . . . u2n. . .
...
0 1
= LU
lii = dii, i = 1(1)n, lij = lijdii, i = 2(1)n, j = 1(1)i 1
Crout . , -
A = LDU , - 3.3.1
A =
1l21 1
l31 l32 1 0...
......
. . ....
......
. . .
lr1 lr2 lr3 . . . lr,r1 1lr+1,1 lr+1,2 lr+1,3 . . . lr+1,r1 lr+1,r1...
......
......
. . .
ln1 ln2 ln3 ln,r1 ln,r . . . 1
d11 0
d22. . .
0 dnn
1 u12 . . . u1r u1,r+1 . . . u1n. . .
......
.... . .
......
...
1 ur,r+1 . . . urn1 . . . ur+1,n
0 . . ....
1
110
-
A =
1l21 1
l31 l32 1 0...
......
. . ....
......
. . .
lr1 lr2 lr3 . . . lr,r1 1lr+1,1 lr+1,2 lr+1,3 . . . lr+1,r1 lr+1,r 1...
......
......
. . .
ln1 ln2 ln3 ln,r1 ln,r . . . 1
d11 d11u12 . . . d11u1r d11u1,r1 . . . d11u1n. . .
......
.... . .
......
...
drr drrur,r+1 . . . drrurn. . .
...
0 . . ....
dnn
d11 = a11d11u12 = a12
...
d11u1n = a1n
d11 = a11
uij =aijd11
, j = 2(1)n.
111
-
l21d11 = a21...
ln1d11 = an1
li1 =ai1d11
, i = 2(1)n.
arr =r1j=1
lrj djj ujr + drr, r = 2(1)n
arp =r1j=1
lrj djj ujp + drr urp, p = r + 1(1)n
apr =
r1j=1
lpr djj ujr + lpr drr, p = r + 1(1)n
, L,D U
drr = arr r1j=1
lrj djj ujr
urp =
(arp
r1j=1
lrj djj ujp
)/ drr
lrp =
(arp
r1j=1
lpj djj ujr
)/ drr
p = r + 1(1)n, r = 1(1)n
A = L(DU) = LU
112
-
1 0l21 1...
. . .
ln1 . . . 1
u11 . . . . . . u
1n
. . ....
. . ....
0 unn
= LU
uii = dii, i = 1(1)n uij = di uij = a
(i)ij , i = 1(1)n, j = 1(1)n
Doolittle .
A LU - (L 6= UT ).
A = LDLT (3.85)
L . - D
D1/2 = diag(d1/211 , . . . , d
1/2nn ) (3.86)
A
A = LDLT = (LD1/2)(LD1/2)T = LLT
(3.87)
L = LD1/2. (3.88)
A
A = LLT .
Cho-
leski
Cho-
leski . -
Choleski.
113
-
. A x 6= 0
xTAx > 0
xTAx 0
A mn , B = ATA ,
BT = (ATA)T = ATA = B.
B . , x 6= 0 y = Ax,
xTBx = xTATAx = yTy =
ni=1
y2i 0.
(rank) A n, x 6= 0 y = Ax 6= 0, xTBx > 0 B .
3.4.2. A n n A .
. x 6= 0 Ax = 0
xTAx = 0
A . Ax = 0 A .
3.4.3. 1
.
1 A
A, i1 0, i =1(1)n ( ;). 3.3.1
l11 = u11 =a11
A
lj1 =aj1u11
=a1jl11
= u1j , j = 2(1)n (3.90)
U - L.
115
-
k < n k U - k L.
k + 1 U k+1 L. L U
lj,k+1 = 0 = uk+1,j, j = 1, 2, . . . , k.
A
lk+1,k+1 uk+1,k+1 = ak+1,k+1 k
j=1
lk+1,j uj,k+1
lk+1,k+1 uk+1,k+1 = ak+1,k+1 k
j=1
l2k+1,j
(. 4.1 3.3.1)
lk+1,k+1 = uk+1,k+1 =
(ak+1,k+1
kj=1
l2k+1,j
)1/2. (3.91)
(3.91) . -
Ak+1 3.4.3. -
.
0 < det (Ak+1) = det (Ak)lk+1,k+1 uk+1,k+1
det (Ak) > 0,
lk+1,k+1 uk+1,k+1 > 0
lk+1,k+1 (3.91) - . (.
4.2 3.3.1)
116
-
lp,k+1 =
(ap,k+1
kj=1
lpj uj,k+1
)/ uk+1,k+1
=
(ak+1,p
kj=1
ujp lk+1,j
)/ lk+1,k+1
= uk+1,p, p = k + 2(1)n.
3.4.1 Choleski
n n A :
1. n aij , i, j = 1(1)n A.
2. l11 =a11
3. j = 2(1)n lj1 = aj1/l11
4. r = 2(1)n 1 4.1-4.24.1
lrr =
[arr
r1j=1
l2rj
]1/2. (3.92)
4.2 p = r + 1(1)n
lpr =1
lrr
[apr
r1j=1
lpj lrj
](3.93)
5.
lnn =
[ann
n1j=1
l2nj
]1/2(3.94)
6. lrp, p = 1(1)r, r = 1(1)n. .
. Choleski
-
.
117
-
3.5 LU
3.3 -
Gauss
.
;
.
3.5.1. n n A P , L U PA
PA = LU (3.95)
. (. [Young and Gregory] . 127-129).
-
Gauss PA A .
PA. detP 6= 0 Ax = b
PAx = Pb (3.96)
A - PA. Wilkinson [1967] PA - P .
Gauss -
, A a11 . -
(3.77) (3.78)
U L, . A
118
-
u11 u12 u13 . . . u1n b1 0l21 a22 a23 . . . a2n b2 0l31 a32 a33 . . . a3n b3 0. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .ln1 an2 an3 . . . ann bn 0
.
,
. r
sr = arr r1j=1
lrj ujr
sr+1 = ar+1,r r1j=1
lr+1,j ujr
. . . . . . . . . . . . . . . . . . . . . . . . . . . (3.97)
sn = anr r1j=1
lnj ujr
.
r = 2
u11 u12 u13 . . . u1n b1 0l21 a22 a23 . . . a2n b2 s2l31 a32 a33 . . . a3n b3 s3. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .ln1 an2 an3 . . . ann bn sn
(3.97) r = 1
s1 = a(1)11 s2 = a
(1)21 . . . sn = a
(1)n1 .
119
-
r = 2
s2 = a(1)22 l21 u12
= a(1)22 +m21 a
(1)12
= a(2)22
s3 = a(2)32 , . . . , sn = a
(2)n2
sr = a(r)rr sr+1 = a
(r)r+1,r, . . . , sn = a
(r)nr (3.98)
si. p
|sp| = maxrin
|si| . sr r p (r < p) sp sr.
urr = sr
r u
urp = ar,p r1j=1
lrj ujp, p = r + 1(1)n
r L
lpr = sp/urr, p = r + 1(1)n
.
, -
L. , lij - / Gauss
.
120
-
3.5.1 LU -
A LU - Lz = b Ux =z L U .
1. n, aij , i = 1(1)n, j = 1(1)n+ 1 A lii, i = 1(1)n L uii, i = 1(1)n U .
2. p 1 p n
|ap1| = max1jn
|aj1|
( )
|ap1| = 0 ( ). .3. p 6= 1 p 1 A.4. l11 u11
l11 u11 = a11
5. j = 2(1)n
u1j = a1j/l11 ( U)lj1 = aj1/u11 ( L)
6. r = 2(1)n 1 6.1-6.4.6.1 p r p n
apr r1j=1
lpj ujr
= maxrknakr
r1j=1
lkj ujr
( )
( -
)
121
-
6.2 p 6= r p r A L.
6.3 lrr urr
lrr urr = arr r1j=1
lrj ujr
6.4 p = r + 1(1)n
urp =
(arp
r1j=1
lrj ujp
)/lrr (r U)
lpr =
(apr
r1j=1
lpj ujr
)/urr (r L)
7.
hold = ann r1j=1
lnj ujn
hold = 0 ( ). .
lnn unn
lnn unn = ann r1j=1
lnj ujn
( 8 9
Lz = b).
8.
z1 = a1,n+1/l11
9. i = 2(1)n
zi =
(ai,n+1
i1j=1
lij zj
)/ lii
122
-
( 10 11
Ux = z)
10.
xn = zn/unn
11. i = n 1(1)1
xi =
(zi
nj=i+1
uij xj
)/ uii
12. xi, i = 1(1)n. .
3.5.2
b1x1 +c1x2 = d1a2x1 +b2x2 +c2x3 = d2
a3x2 +b3x3 +c3x4 = d3. . . . . .
. . . . . .an1xn2 +bn1xn1 +cn1xn = dn1
anxn1 +bnxn = dn(3.99)
Gauss .
.
Gauss
.
ai, . ci . b1 6= 0 x1 ,
123
-
m1 = a2b1
b2x2 + c2x3 = d2
b2 = b2 +m1c1
d2 = d2 +m1d1
b2 6= 0, x2 , /.
m2 = a3b2
b3x3 + c3x4 = d3
b3 = b3 +m2c2
d3 = d3 +m2d2
i- , xi i + 1, /
mi = ai+1bi
(3.100)
i+ 1
bi+1xi+1 + ci+1xi+2 = di+1 (3.101)
bi+1 = bi+1 +mici (3.102)
124
-
di+1 = di+1 +midi (3.103)
i = 1(1)n 1
b1x1+ c1x2 = d1
b2x2+ c2x3 = d2
. . .. . .bn1xn1+ cn1xn = d
n1
bnxn = dn
(3.104)
b1 = b1 d1 = d1.
xn =dnbn, bn 6= 0 (3.105)
xi = (di cixi+1)/ bi, i = n 1(1)1
bi 6= 0. .
1. n A, bi, i = 1(1)n, ci, i = 1(1)n 1, ai, i = 2(1)n di, i = 1(1)n
2. i = 1(1)n 1 2.1-2.32.1
mi = ai+1bi
2.2
bi+1 = bi+1 +mici
2.3
di+1 = di+1 +midi
( )
125
-
3. bn = 0 ( ). .
4.
xn =dnbn
5. n 1(1)1
xi = (di cixi+1)/bi6. xi, i = 1(1)n. .
LU . A (3n 2) , L U (3n 2).
L =
l1k2 l2 0
k3 l3
0 . . . . . .kn ln
U =
1 u11 u2 0
1 u3. . .
. . .
0 1 un11
(3.106)
(2n1) L (n1) U , (3n 2) A = LU ,
l1 = b1, l1u1 = c1 k2 = a2
k2 u1 + l2 = b2, l2u2 = c2 k3 = a3
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (3.107)
kn un1 + ln = bn kn = an
126
-
l1 = b1
u1 = c1/l1
ki = ai, i = 2(1)n
li = bi ki ui1, i = 2(1)nui = ci/li, i = 2(1)n 1 (3.108)
l1 = b1
u1 = c1/l1
li = bi ai ui1, i = 2(1)n (3.109)ui = ci/li, i = 2(1)n 1
(3.99)
LUx = d
Lz = d (3.110)
Ux = z. (3.111)
(3.110)
z1 = d1/l1 (3.112)
zi = (di ai zi1)/li, i = 2(1)n (3.111)
xn = zn (3.113)
xi = zi ui xi+1, i = n 1(1)1. Grout
(3.99)
127
-
1. n A, bi, i = 1(1)n, ai, i = 2(1)n, ci, i = 1(1)n 1 di, i = 1(1)n
2.
l1 = b1
u1 = c1/l1
3. i = 2(1)n 1
li = bi ai ui1ui = ci/li
4.
ln = bn an un1( 5 6 Lz = d).
5.
z1 = d1/l1
6. i = 2(1)n
zi = (di ai zi1) / li( 7 8 Ux = z).
7.
xn = zn
8. i = n 1(1)1
xi = zi ui xi+1
128
-
9. xi, i = 1(1)n. .
2 1 0 01 2 1 00 1 2 10 0 1 2
x1x2x3x4
=
1001
Grout
1. n = 4, b1 = b2 = b3 = b4 = 2, a2 = a3 = a4 = 1c1 = c2 = c3 = 1 d1 = 1, d2 = 0, d3 = 0 d4 = 1
2. l1 = 2, u1 = 1/23. i = 2
l2 = b2 a2 u1 = 2 (1)(1
2
)= 3
2
u2 = c2/l2 = 1/(32
)= 2
3
i = 3
l3 = b3 a3 u2 = 2 (1)(2
3
)= 4
3
u3 = c3/l3 = 1/(43
)= 3
4
4. l4 = b4 a4 u3 = 2 (1)(3
4
)= 5
4
5. z1 = d1/l1 = 1/2
6. i = 2
z2 = (d2 a2 z1)/l2 = 0(1)(12)
( 32)= 1
3
i = 3
x3 = (d3 a3 z2)/l3 = 0(1)(13)
( 43)= 1
4
i = 4
z4 = (d4 a4 z3)/l4 = 1(1)(14)
( 54)= 1
7. x4 = z4 = 1
129
-
8. i = 3
x3 = z3 u3 x4 = 14 (3
4
) 1 = 1i = 2
x2 = z2 u2 x3 = 13 (2
3
) 1 = 1i = 1
x1 = z1 u1 x2 = 12 (1
2
) 1 = 1 x1 = x2 = x3 =x4 = 1
3.5.2. A (3.110) ai, ci 6= 0 i = 2(1)n1. |b1| > |c1|, |bi| |ai|+ |ci| i = 2(1)n1 |bn| > |an|, detA 6= 0 i)|ui| < 1, ii)|ci| 0, A = 0 A = 0ii)cA = |c| A c iii)A+B A+ B (3.123)iv)AB A B.
137
-
norms norms -
A = maxx=1
{Ax}
Ax A x. (3.124)
3.6.4. norms -
norms
A1 = max
ni=1
|ai|
A2 = [S(AHA)]1/2 (3.125)
A = maxi
n=1
|ai|
S(A) = max1in
|i| i A AH A.
. .
norms -
.
{x(k)}, k = 0, 1, 2, . . . {x(k)i }, i = 1(1)n {x(k)i }, k =0, 1, 2, . . . i = 1(1)n ,
limk
x(k) = 0 x(k) k
0
3.6.5.
limk
x(k) = x
138
-
limk
x(k) x = 0.
. .
{A(k)}, k = 0, 1, 2, . . . - {a(k)ij }, i, j = 1(1)n - n2
{a(k)ij }, k = 0, 1, 2, . . . i, j = 1(1)n , -
limk
A(k) = 0 A(k) k
0.
3.6.6.
limk
A(k) = A
limk
A(k) A = 0.
. .
3.6.7.
A n, , lim
kA(k) = 0
S(A) < 1. (3.126)
. (. [Golub and Van Loan])
3.6.8. n
Ak Ak, k = 0, 1, 2, . . .. k = 0, 1 . k > 1
Ak = Ak1A Ak1 A = Ak2A A Ak2 A2 Ak.
139
-
3.6.9.
A n -, lim
kA(k) = 0
A < 1.
. 3.6.6 limk0
Ak = 0 limk
Ak = 0 3.6.8 lim
kAk = 0,
A < 1.
3.6.10. A n
S(A) A. (3.127)
. A x -
Ax = x
norms
Ax = x norms
|| x A x
|| A
S(A) = max || A.
3.6.11.
m=0
Am = I + A+ A2 + + Am + . . .
140
-
limm
Am = 0.
m=0
Am = (I A)1.
. (i) limm
Am = 0
3.6.7 S(A) < 1 = 1 A. det(I A) 6= 0 (I A)1 .
(I A)(I + A+ A2 + + Am) I Am+1
I + A+ A2 + + Am (I A)1 (I A)1Am+1.
I + A+ A2 + + Am m
(I A)1.(ii)
S(m) = I + A+ A2 + + Am m
(I A)1
S(m)ij (I A)1ij , m
n2 S(m)ij -
.
m- . i j (Am)ij 0 m lim
mAm = 0.
3.6.1.
m=0
Am = (I A)1
S(A) < 1.
141
-
.
3.6.7 3.6.11.
3.6.2. norm
A < 1
m=0
Am = (I A)1.
.
3.6.9 3.6.11.
3.6.12. A < 1 norm I A I + A
1
1 + A (I A)1 1
1 A (3.128)
1
1 + A (I + A)1 1
1 A . (3.129)
. 3.6.10 S(A) A < 1 = 1 A det(I A) 6= 0 I A . (3.128)
I = (I A)(I A)1. norms
1 = I = (I A)(I A)1 I A (I A)1 (I+ A) (I A)1 = (1 + A) (I A)1.
(3.128).
(I A)1 = (I A+ A)(I A)1 = I + A(I A)1
norms
(I A)1 = I + A(I A)1 I+ A(I A)1 1 + A (I A)1.
,
A < 1, (3.128). (3.128) A A (3.129).
142
-
3.7
, -
-
.
Ax = b
,
B = [A, b].
, -
-
.
. -
A b. A b A b,. , -
,
x, x.
(A+ A)(x+ x) = b+ b (3.130)
.
3.7.1. A
A1 A < 1 (3.131)
xx
1 A A1[bb +
AA
](3.132)
= (A) = A1 A. (3.133)
143
-
. (3.130)
(A+ A) x = b Ax x A + A = A(I + A1 A) .
S(A1A) A1A < 1 (3.131), I + A1A .
x = (I + A1A)1A1(b Ax)
norms
x = (I + A1A)1A1(b Ax) (I + A1A)1 A1 (b Ax).
3.6.12 , A1A A1 A < 1,
(I + A1A)1 11 A1A
11 A1 A .
x A1
1 A1 A [b+ A x]
xx
A A11 A1 A
[ bA x +
AA
].
Ax = b b A x
xx
A A11 A1 A
[bb +
AA
].
144
-
7.2
A = 0
xx A A
1bb .
7.3 b = 0
xx =
A A11 A1 A
AA .
(i) A , 7.2 ( A = 0), (A) = A1 A.
(ii) (A) , A b A b x.
(iii) = A1 A A1 A = I = 1.
A ,
(A) = A A1 (3.134) Ax = b. (A) - , A b x -.
(ill-conditioned).
3.7.2. A ,
(A) =
1n , (3.135)
1 n A, .
. .
145
-
4
4.1
Au = b (4.1)
A u, b - . A ( 106), .
-
. ,
.
.
u(n+1) = Gu(n) + k, n = 0, 1, 2, . . . (4.2)
G k ., (4.2)
:
146
-
1. (4.1), -
().
2. (4.2)
, (4.1) ( -
).
(4.2)
u(0).
4.1.1. (4.2)
S(G) < 1. (4.3)
. u u(n), n =0, 1, 2, . . . e(n) = u(n) u,
e(n+1) = Ge(n) (4.4)
u
u = Gu+ k. (4.5)
(4.4)
e(n) = Gne(0). (4.6)
limn
u(n) = u limn
e(n) = 0 (4.6)
limn
(G(n)e(0)) = 0 e(0). -
3.6.7 limn
Gn = 0
(4.3).
S(G) < 1, I G (I G)u = k . S(G) < 1 lim
nGn = 0 lim
n Gn = 0.
Gne(0) Gn e(0) limn
Gne(0) = 0
(4.6) limn
e(n) = 0 limn
u(n) = u,
(4.2) .
147
-
G
G < 1 (4.7) = 1 S(G) G . -
(4.2) ,
u(0)( ) - (4.2) n = 0, 1, 2, . . .. ,
:
u(n+1) u(n)
u(n+1) u(n) u(n+1)
= 1 2 . (4.2), -
.
e(n) 0 n . (4.6) u(0) 6= u
e(n) / e(0) Gn . (4.8)
Gn norm e(0) . n
Gn . (4.9)
n
Gn 1
n log /(1nlog Gn) (4.10)
x x. (4.10)
148
-
(4.2). -
( 1nlogGn).
Rn(G) = 1nlog Gn . (4.11)
,
R(G) = limn
Rn(G) = logS(G) (4.12)
[34]
S(G) = limn
( Gn 1n ).
( )
(4.2) -
n logR(G)
. (4.13)
(4.12) -
G . -
-
-
.
4.2
(4.2). -
(4.1) A1, . -
A1 , (4.1)
R1, R1Au = R1b, (4.14)
149
-
R - (
Rs = t ). (4.14)
u(n+1) = u(n) + R1(bAu(n)), n = 0, 1, . . . (4.15) 6= 0
(4.15). -
(4.15)