К.Ю. Богачёв - Практикум на ЭВМ. Методы приближения функций (1133845), страница 11
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,56H 67>>D 4.6 9.23767//.; 9.2/+,-B f (xi;1 xi ) ;06;7-,; :95C65?7/57>1 f 0(xi ) ,670., . f (xi xi+1 ) ;06;7-,; :95C65?7/57> 1 f 0(xi) ,:9.0.. >7-+37 15>D I-5 :95C65?7/5; H,973/;F-,; , 07,.>5, 1+-+9D7 -7> C+6BE7, 47>>7/BE7 =6.31+,-B @H/1<55 /. ,+,73/7> +-97217. 1+/4.-76B/.; @+9>H6. 36;.. !"# # $#x19. '&+-.- 0*-0* 70.-71+:973767/5; :.9.>7-9. di 0 +CG78 ,A7>7 5/-79:+6;<55 1H,+4/+-1HC547,15>5@H/1<5;>5 5>77- 0538> wi+1f (xi;1Y xi) + wi;1 f (xiY xi+1) 7,65 wi2+1 + wi2;1 6= 0><w+w(8)di = (x ; x )fi(+1x Y xi;1>i+1ii;1 i ) + (xi ; xi;1 )f (xi Y xi+1 )> 7,65 wi+1 = wi;1 = 0:xi+1 ; xi;1=37 i = 3 4 : : : n ; 2 5wj = jf (xj Y xj+1) ; f (xj;1Y xj )j :73+,-.FG57 2/.47/5; d1 d2 5 dn;1 dn 0 :95=9./54/DA H26.A 0DC59.F-,;, 5,A+3; 52 -+8 565 5/+8 3+:+6/5-76B/+8 5/@+9>.<55 + @H/1<55 f (,>.
/5?7).,/+0/D7 %% 5$>!@<= 7 Pf :1) Pf ;06;7-,; 1H,+4/+->/+=+467//+8 @H/1<578, 2/.47/5; 1+-+9+8 2.05,;- -+6B1+ +- 6+1.6B/+=+ :+0737/5; @H/1<55 f , 5>7//+: 2/.47/5; Pf/. +-97217 Sxi xi+1 ] 2.05,;- -+6B1+ +- 2/.47/58 @H/1<55 f 0 -+41.Axi;2 xi;1 xi xi+1 xi+2 xi+3 .2) 7-+3 :95C65?7/5; /7 ;06;7-,; 65/78/D>: P (f + g) 6= Pf + Pg , A+-;P (f ) = Pf .
3. (C72 3+1.2.-76B,-0.). f 2 C (2) (Sa b]) , # 9f Pf C (x3 xn;2]) const h2 f C (2)(a b]) k; kkkh (5).+=97E/+,-B .::9+1,5>.<55 /. +-9721.A Sx1 x3] 5 Sxn;2 xn] 2.05,5- +- ,:+,+C. 0DC+9. 2/.47/58 d1 d2 5 dn;1 dn .x 19.6. ; $5!;7; > )! 5!"6% $6#!& $6J-+- >7-+3 :95C65?7/5; 5,:+6B2H7-,; 36; :+6H47/5; :95C65?.FG78 @H/1<55 Pf , :790.; 5 0-+9.; :9+520+3/.; 1+-+9+8 +=9./547/D 9.23767//+8 9.2/+,-BF @H/1<55 f (-.7. :95C65?7/57> 1 f 0 ).
7C+6BE57 -97C+0./5; 1 =6.31+,-5:95C65?.7>+8 @H/1<55 f :+20+6;F- 5,:+6B2+0.-B I-+- >7-+3 0 -+> ,6H4.7,1+=3. 2/.47/5; @H/1<55 0 -+41.A 2.3./D , /71+-+9+8 :+=97E/+,-BF.H,-B 0 -+41.A a = x1 < x2 < : : : < xn = b 5207,-/D 2/.47/5; @H/1<55f (x1 ) : : : f (xn). .9.>7-9 di , i = 2 3 : : : n ; 1 0 +CG78 ,A7>7 5/-79:+6;<551H,+4/+-1HC547,15>5 @H/1<5;>5 :+6.=.7-,; 9.0/D>8>sign f (xiY xi+1)min fjf (xi;1Y xi)j jf (xiY xi+1)jg ><di = >7,65 sign f (xi;1 Y xi) = sign f (xi Y xi+1)(9)>:05/.47..
!"# # $#x19. '&+-.- 072*-0* 70.-6H4.8 sign f (xi;1Y xi) 6= sign f (xiY xi+1) ,++-07-,-0H7- ,5-H.<55, 1+=3. 0 -+417 xi :95C65?7/57 f (xi;1 Y xi) 1 f 0 ,670. =+0+95-, 4-+ @H/1<5; 0+29.,-.7- (HCD0.7-) /. +-97217 Sxi;1 xi ], . :95C65?7/57 f (xiY xi+1 ) 1 f 0 ,:9.0. H-079?3.7-,4-+ @H/1<5; ,++-07-,-07//+ HCD0.7- (0+29.,-.7-) /. +-97217 Sxi xi+1]. 673+0.-76B/+, /. +-97217 Sxi;1 xi+1] :9+5,A+35- 52>7/7/57 A.9.1-79. >+/+-+//+,-5@H/1<55 5 >D :+6.=.7> f 0 (xi) di = 0. ,6H4.7 sign f (xi;1 Y xi) = sign f (xiY xi+1 ) A.9.1-79 >+/+-+//+,-5 @H/1<55 /.+-97217 Sxi;1 xi+1 ] /7 52>7/;7-,; 5 0 1.47,-07 di 0DC59.7-,; :95C65?7/57 1 f 0, /.5>7/BE5> >+3H67>.73+,-.FG57 2/.47/5; d1 5 dn 0 =9./54/DA H26.A 0DC59.F-,;, 5,A+3; 52-+8 565 5/+8 3+:+6/5-76B/+8 5/@+9>.<55 + @H/1<55 f (,>. /5?7).,/+0/D7 %% 5$>!@<= 7 Pf :1) Pf ;06;7-,; 1H,+4/+->/+=+467//+8 @H/1<578, 2/.47/5; 1+-+9+8 2.05,;- -+6B1+ +- 6+1.6B/+=+ :+0737/5; @H/1<55 f , 5>7//+: 2/.47/5; Pf/.
+-97217 Sxi xi+1 ] 2.05,;- -+6B1+ +- 2/.47/58 @H/1<55 f 0 -+41.Axi;1 xi xi+1 xi+2 .2) 7-+3 :95C65?7/5; /7 ;06;7-,; 65/78/D>: P (f + g) =6 Pf + Pg , A+-;P (f ) = Pf .(C72 3+1.2.-76B,-0.). f2C(2)(Sa b]) , # ! 4.kf ; Pf kC x2 x ;1 const h kf kC(2) a b (h k(Pf ) kC a b 23 ik(Pf ) kC a b 6 i000((])maxmax=2 3 ::: n;22])(])(5). % :jf (xiY xi )j(max xxi ; ;x xi jf (xiY xi )j xxi ;;xxi jf (xiiiii=1 2 ::: n;1])n+1+2;1+12+1;1;1;1Y xi )j2)+=97E/+,-B .::9+1,5>.<55 /. +-9721.A Sx1 x2] 5 Sxn;1 xn] 2.05,5- +- ,:+,+C.
0DC+9. 2/.47/58 d1 5 dn .x 19.7.$5!;7; > 5!H,-B 0 -+41.A a = x1 < x2 < : : : < xn = b 5207,-/D 2/.47/5; @H/1<55f (x1 ) : : : f (xn).5$#!. :6.8/+> :+9;31. m /.2D0.7-,; @H/1<5;, 1+-+9.; /. 1.?3+> +-97217 Sxi xi+1 ], i = 1 2 : : : n ; 1 ,+0:.3.7- , >/+=+467/+> Pi ,-7:7/5 m5 ;06;7-,; @H/1<578 16.,,. C (m;1) (Sx1 xn])... !"# # $#x19. '&+-.- 0*-0* 70.-73/-79:+6;<5; 1HC547,15>5 ,:6.8/.>5 (m = 3) 5,:+6B2H7-,; 36; :+6H47/5; /.5C+677 =6.31+8 :95C65?.FG78 @H/1<55 Pf 0 9.,,>.-950.7>+> 16.,,71H,+4/+-1HC547,15A >/+=+467/+0..9.>7-9D di , i = 1 2 : : : n 0 +CG78 ,A7>7 5/-79:+6;<55 1H,+4/+1HC547,15>5 @H/1<5;>5 0DC59.F-,; 52 H,6+05; Pf 2 C (2) (Sa b]), -.7.Pi00;1(xi) = Pi00(xi ) i = 2 3 : : : n ; 1:(10)2 :973,-.067/5; >/+=+467/. Pi 0 0537 (2) /.A+35>(11)Pi00;1(xi ) = 2c3 i;1 + 6c4 i;1(xi ; xi;1 ) Pi00(xi) = 2c3 i:+3,-.06;; I-5 2/.47/5; 0 (10), 5>77>2c3 i;1 + 6c4 i;1(xi ; xi;1 ) = 2c3 ii = 2 3 : : : n ; 1: :+>+GBF (3) /.A+35>3f (xi;1Y xi) ; 2di;1 ; di + 3(x ; x ) di;1 + di ; 2f (xi;1Y xi) =ii;1xi ; xi;1(xi ; xi;1 )2= 3f (xiY xi+1 ) ; 2di ; di+1 :xi+1 ; xi-.7.(xi+1 ; xi )(3f (xi;1Y xi) ; 2di;1 ; di + 3di;1 + 3di ; 6f (xi;1Y xi)) == (xi ; xi;1 )(3f (xiY xi+1 ) ; 2di ; di+1)97+C9.2H7> I-+ 9.07/,-0+:(xi+1 ; xi)(di;1 + 2di ; 3f (xi;1Y xi)) = (xi ; xi;1 )(3f (xiY xi+1) ; 2di ; di+1)565(xi+1 ; xi )di;1 + 2(xi+1 ; xi )di + 2(xi ; xi;1)di + (xi ; xi;1 )di+1 == 3f (xi;1Y xi)(xi+1 ; xi) + 3f (xiY xi+1)(xi ; xi;1 )673+0.-76B/+,(xi+1 ; xi)di;1 + 2(xi+1 ; xi;1 )di + (xi ; xi;1 )di+1 == 3f (xi;1Y xi )(xi+1 ; xi ) + 3f (xiY xi+1)(xi ; xi;1)(12)i = 2 3 : : : n ; 1:J-+ ,5,-7>.
52 n ; 2 65/78/DA H9.0/7/58 +-/+,5-76B/+ n /75207,-/DAd1 d2 : : : dn . 6; 77 2.>D1./5; -97CH7-,; 7G7 30. H9.0/7/5;, 1+-+9D7 ,-9+;-,;, 5,A+3; 52 -+8 565 5/+8 3+:+6/5-76B/+8 5/@+9>.<55 + @H/1<55 f (,>./5?7).5,-7>. (12) ;06;7-,; ,5,-7>+8 H9.0/7/58 , -97A35.=+/.6B/+8 >.-95<78 ,(,-9+=5>) 35.=+/.6B/D> :97+C6.3./57> 5 77 >+?/+ 97E.-B >7-+3+> .H,,.
C720DC+9. =6.0/+=+ I67>7/-..,/+0/D7 %% 5$>!@<= 7 Pf :.. !"# # $#x19. '&+-.- 074*-0* 70.-1) Pf ;06;7-,; /76+1.6B/+8 1H,+4/+->/+=+467//+8 @H/1<578, 2/.47/5; 1+-+9+8 2.05,;- +- :+0737/5; @H/1<55 f 0 1.?3+8 -+417 x1 x2 : : : xn .2) 7-+3 :95C65?7/5; ;06;7-,; 65/78/D>: P (f + g) = Pf + Pg , P (f ) =Pf .+=97E/+,-B .::9+1,5>.<55 1HC547,15>5 ,:6.8/.>5 (0 ,56H /76+1.6B/+,-5,:6.8/.) 2.05,5- +- 0DC+9. 3+:+6/5-76B/DA H9.0/7/58 36; 2.>D1./5; ,5,-7>D (12) 5 ,+,-.06;7- +- O(h2) 3+ O(h4), =37 h +:97376;7-,; 9.07/,-0+> (5).x 19.8.5$#! #<= )$&!% >7-+3.A, 526+?7//DA 0 x 19.4 5 x 19.6, -97CHF-,; 30. 3+:+6/5-76B/DA H,6+05; 36; +:973767/5; :.9.>7-9+0 d1 5 dn , 0 >7-+37 52 x 19.5 -97CHF-,; 47-D973+:+6/5-76B/DA H,6+05; 36; +:973767/5; :.9.>7-9+0 d1 d2 5 dn;1 dn . >7-+37 :95C65?7/5; 1HC547,15>5 ,:6.8/.>5 (x 19.7) -97CHF-,; 30.
3+:+6/5-76B/DAH9.0/7/5; 36; 2.>D1./5; ,5,-7>D 65/78/DA H9.0/7/58. ,:+6B2HF-,; /7,1+6B1+ >7-+3+0 :+,-9+7/5; 3+:+6/5-76B/DA H,6+058, 1+-+9D7 0DC59.F-,; 0 2.05,5>+,-5 +- -+=+, 1.1.; 3+:+6/5-76B/.; 5/@+9>.<5; 5207,-/. + :95C65?.7>+8@H/1<55.x 19.8.1.5$#! #<= )$& !% 56%& 6; 5$% 5$6%# 7 % )$&6!H,-B 5207,-/D 2/.47/5; f 0(x1 ) 5 f 0(xn) :9+520+3/+8 f 0 @H/1<55 f 0 =9./54/DA H26.A x1 5 xn . +=3.
:+6.=.7>d1 = f 0(x1 )dn = f 0(xn ):(13) >7-+3.A, 526+?7//DA 0 x 19.4, x 19.5 5 x 19.6, 9.07/,-0. (13) 3.F- /73+,-.FG57 2/.47/5; :.9.>7-9+0 d1 5 dn . >7-+37 :95C65?7/5; 1HC547,15>5,:6.8/.>5 (x 19.7) 9.07/,-0. (13) ;06;F-,; 30H>; /73+,-.FG5>5 H9.0/7/5;>5,1+-+9D7 36; ,+A9./7/5; -97A35.=+/.6B/+,-5 ,5,-7>D (12) /.3+ ,376.-B ,++-07-,-07//+ :790D> 5 :+,673/5> H9.0/7/5;>5 I-+8 ,5,-7>D./-79:+6;<5; 1HC547,15>5 ,:6.8/.>5 , 5,:+6B2+0./57> I-+=+ ,:+,+C.
0DC+9. =9./54/DA H,6+058 3.7- ,:6.8/ Pf , 1+-+9D8 /.2D0.F- #!"&5!. 7H6H4E.7>D7 +<7/15 7=+ :+=97E/+,-5kf ; Pf kC(a b]) 3845 h4kf (4)kC(a b])kf 0 ; (Pf )0kC(a b]) 241 h3kf (4)kC(a b])=37 h +:97376;7-,; 9.07/,-0+> (5)... !"# # $#x19. '&+-.- 0*-0* 70.-75x19.8.2. 5$#! #<= )$& !% 56%& 6; %$ 5$6%# 7 % )$&6!H,-B 5207,-/D 2/.47/5; f 00(x1 ) 5 f 00(xn) :9+520+3/+8 f 00 @H/1<55 f 0 =9./54/DA H26.A x1 5 xn . +=3. :+-97CH7> +- :95C65?.FG78 @H/1<55 Pf(Pf )00(x1 ) = f 00(x1 )(Pf )00(xn) = f 00(xn)-.7.P100(x1 ) = f 00(x1 ) Pn00;1(xn) = f 00(xn):(14)2 (11) /.A+35>P100(x1 ) = 2c3 1 Pn00;1(xn ) = 2c3 n;1 + 6c4 n;1(xn ; xn;1 ):+3,-.06;; I-5 2/.47/5; 0 (14), 5>77>2c3 1 = f 00(x1 )2c3 n;1 + 6c4 n;1(xn ; xn;1) = f 00(xn ): :+>+GBF (3) /.A+35>2 3f (x1Y x2 ) ; 2d1 ; d2 = f 00(x1 )x2 ; x12 3f (xn;1Y xn) ; 2dn;1 ; xdn ;+ x3(dn;1 + dn ; 2f (xn;1Y xn)) = f 00(xn ):-.7.nn;12 3f (x1Y xx2);;x2d1 ; d2 = f 00(x1 ) 2 dn;1 + 2xdn ;; x3f (xn;1Y xn) = f 00(xn ):21.:5E7> I-5 0D9.?7/5; 0 0537nn;12d1 + d2 = 3f (x1Y x2 ) ; 1 f 00 (x1)(x2 ; x1 )2(15)100dn;1 + 2dn = 3f (xn;1Y xn) + 2 f (xn)(xn ; xn;1) >7-+3.A, 526+?7//DA 0 x 19.4 5 x 19.6, 9.07/,-0.
(15) :+20+6;F- +:973765-B/73+,-.FG57 2/.47/5; :.9.>7-9+0 d1 5 dn , :+,1+6B1H :.9.>7-9D d2 5 dn;15207,-/D (,>. ,++-07-,-07//+ (7) 565 (9)). >7-+37 15>D (x 19.5), =37 -97CHF-,; 4 :.9.>7-9. d1 d2 5 dn;1 dn , 9.07/,-0. (15) :973,-.06;F- ,+C+8 ,0;2B >7?3H I-5>5 :.9.>7-9.>5. ,65, /.:95>79, 5207,-/D 7G7 5 2/.47/5; f 0(x1 ) 5 f 0(xn ), +- d1 5 dn +:97376;F-,; 529.07/,-0 (13), . d2 5 dn;1 /.A+3;-,; 52 H9.0/7/58 (15). >7-+37 :95C65?7/5; 1HC547,15>5 ,:6.8/.>5 (x 19.7) 9.07/,-0. (15) ;06;F-,; 30H>; /73+,-.FG5>5 H9.0/7/5;>5, 1+-+9D7 36; ,+A9./7/5; -97A35.=+/.6B/+,-5 ,5,-7>D (12) /.3+ ,376.-B ,++-07-,-07//+ :790D> 5 :+,673/5> H9.0/7/5;>5 I-+8 ,5,-7>D...