Αριθμητική Ανάλυση

280
Εισαγωγή στην ΑΡΙΘΜΗΤΙΚΗ ΑΝΑΛΥΣΗ Ν. Μισυρλής y x { f( ) á á î x 2 x 1 x 0 M 0 P 0 y = f(x) f(b) b } è ΑΘΗΝΑ 2008

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Βιβλίο Αριθμητικής Ανάλυσης

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)