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Unit I. 5
(rANSCEnds
  
 
 
  
    
8 84 ty \
the
  
fy
4
Witter, Nhe
i}
gotttion +? Erroyy
‘oo major ¢ 1
ihre major CatexOring “meri, '
1) Inherent erroy . ay
for Vos
jata, for Which the po 8® err
the inherent error person TH ape,
ihe statement of the ca be
oblem
Def
 
(2) Round off error
procedure. While all C8 erry,
inconvenient to wor TE with
approximations to an all de
approximations lead tg litate.
off errors. The round off tier ¢ f
added to‘ the finite , ese
é epresentati SWantity
a ion of a ¢
make it the true Tepresentation of the ; Sonoma
6 DUM ber
Example (1) 28. 63243 becomes 28, 63
correctly to four signi
00243. ignificant figures. The mund of
when toun
 
 
(2) 18, 9673 becomes 18. 97 when rounded vif correctly ty fou
significant figures. The round off error is - 0027 :
(3) Truncation error : These are errors caused
approximate formula in computation. For example.
 
we
i 3 ty
infinite series, ¢= 1+ 7 +7 qt
$ Fthe above infinite sens
Suppose we find the sum of iit an
the first 10 terms- The terms = on
the calculation of & This type of
| i merical
error. rors encountered in nu
a, Bxplain any tH tos Ap 98
methods with exam?
Solution +
  
 
See question 1.2
516 NUMERICAL METHODS IN SCIENCE AND ENGG, “s
fit) =f lng) +(e —X9) F (ys Xy) + Ot Xp) (2 = AyIf Cy , Xp, 49) + CD)
Here xp = 141 = 2, 22 = 43 f (tg) = 43 f lq, £1) = 1, Fa, 1,42) =
All the remaining helper order differences are zero.
Substituting these values in (1),
fix)=4+(8-1)4 &-1)@-2)1
 
9. State Lagrange’s interpolation formula (Ap 95
Bharathidasan Uty ; Oct 97 B. Tech M.LU. ; Oct 95 WLU.)
Solution : Let »=f(x) be a function which takes the values
Yo sR se 3p, Corresponding to x=2y , 27, .--%p
 
"s interpolation formula is
(x —24) (2-29) «.. l2— 2)
.) = ——<—— rade
‘ (xq — Xq) (tq —Xg) .... (39 — Xp) 78
 
(ty —%q) (4 - r
 
(2 —Xy) IX — x4) 2. (2 —Xy 1)
pe Oy
&,—%5) &,—*) - @,—*, 9) 2"
10. What is the Lagrange’s formula to find y, if three
sets of values (xp, yo) ,(xy 471) and (x2 ,y2) are given?
 
(Oct 97 MU.)
Solution :
Pe (may) ap) ea) = H2)
Gp—%y) 32) 2°* Gy xq) =) 7
x= a5) =x)
* Gey a0) ==)7
pi > IN SCIENC.
ICAL METHODS IN SCIENCE AND i
50 NUMER Eng,
quation by elimings;
=a: 2 +b: 8%, (Noy
from the relation yx
48. Form the difference ©
aandb
M.K.U, ; Nov 97 M.S.Uty)
Same as worked example 2 on page $12 of the main tox ‘am
(1)
gtly py. get?
Sey EOS
=2'a +363"... (2)
x
Solution : Given y,=a@-2'+6°3°
 
and ¥
=4a2°+9b3"....(3)
We can eliminate the quantities a 2°, 63° from (1), (2) andj, |
by using determinates. The result is "
|sre 49
Jx+1 2 3) =0
% 1
ie. 4 2(2-3)—yy4y (4-9) + yy (12-18) =0
10. ~Jx42+5 yy 41-69, =0
OF Yx+ 25941 #6 y= 0
49. Form difference equation eliminating A and B in
Jn=A 2"+B-5", (Oct 95 MU)
Solution : Given My = As 2" 4B. 50 (1)
Na 1 AQ™ ly Bare
=2A2"4525" (9)
and y, ,y=A-2"*2) peneo
F4AQ"425R5" 1g)
We can liminate the ;
and (3) by using detersinenee na and B “8? from (1), ©) °
3 : result is
Yneg 4.25 a
Yn+1 2 5leg
w. Faaf sh ree Se
 
 
    
  
 
 
  
   
  
  
  
  
  
  
 
    
wet yale
{ prianesntlt At
‘ pgroninniatien
af
the I pwr ills peut
We use the a :
- ya (dy fig at
, h ide mn ,
, Wy ‘
Then Ved v, hf vy) {fe renee appron :
ve the PP di ,
We can alse UP
yo Le fay WD
1 eh fey? wad
Then ¥) 2)
ise the contral diffe
approx
We can also 1 ence app
yay Mad =f (4 I)
i A
Then yy.1=Ij-1 +h FG) wen)
If we replace a by the difference
the method of obtaining ¥j is
this method, the number of i
of y is only one.
If we use the difference
intervals separating the two
This method of solut
method.ND ENGG.
ticular ease
order!
ular case of
predictor
al value
  
 
they do nat
penis tes
1 the step size
ations of the
information
r points and
ood estimate
it methods
j., Nov 97
ie conditio®
we have
 
 
 
 
J gictor formula,
jrathiar Uty)
@ & A - NUMERICAL So,
i "AL SOLUTION OF ¢ Z 1 =
a ITAL DIFFERENTIAL Bountions a ™
ng the formula (1), we ean calculate ¥4 ,¥2 5%
late v4.2 0¥a+
snowing th va :
jnowing the value of yo, This is called an explicit me
e have the
 
thod.
To solye the same di
ed i ,
proved Euler method aco
int
aan
ver 1=VWAG [Fl y+ FO Feed] veel 2)
In (2), there is a difficultly to caleulate y+ 1 S* the
3 of the equation. We therefore
n implicit
value of y;41 Occurs on both sixe:
cannot solve for ¥;41 directly. This is known 35 al
method.
Note : Implicit
and explicit methods will also arise in numerical
solution of partial differential equations.
42. State the difference between single step and
multistep methods used to solve ordinary differential
ically. (Ap 96 M.U.).
ly the
equations numeri
to solve numerical
in the interv al
: Suppose we want
nber of
Solution +
dy _ %
Y fe, y)giveny Xo)
erval into a finite nur!
 
  
differential equation
We divide this ints
 
[xp - 8) of x.
subintervals by the points
ei eearee (tO< 
such that
ay aja =1.2.0™)
Th x=suti? FAO sPre Nd :
etermine @ number 3, which is an
ical methods, We ge , :
ae to the value of the solution y@) at the point x,
yy is the numerical
 
approximation :
Pap numbers Oy
al equatios-Solution :
Runge-Kutta methods
    
  
 
  
  
    
    
   
» siete jiowing formulas is 4
Kutta formulas of the second ,
b) Picard’.
cs modi ormula dd) Milne's »
(Nov 95
 
 
 
formula is @
    
si Runge-Kutta methods and p
thods for solution of
5, Nov 97 Bharathidasan Upy,
Compar
Cerrector me
problem. ‘Ap 9QA NUMERICAL SOL ingen ty
Nu sol WF shift fh ”
PARTIAL MRK IAA, Iwan =
cy Wa te the bhai |
‘To uae Aduan's ietHead, we wearl nt beat waates Of
y peter tothe required uatie ot y (hp 9% Uhunaihidannn iy
Solution + Muay
Wh. Bay Trae on Malia!»
Mile’ vmethond ii ee well ate bing ivettont
(Nov 04 Hhuruthidowwn Clx
Solution : The statement in aloo
U6, State Milne’s predictor and currector formulae We
solve y= f(a 95 y (ty) Yye atky 1) = Yer WR eBhin ve
y ligt BAy= yy ab are ag 14h, (Ap a MUO
Solution 1 Milie's predictor formulit b
anh
news (ay v0 84 |! ue yi
where elie holween x aig:
Milne's eurroetor formula ti
h fay
wsvorg (vor aries) yg! ti
where € Hien between ag and ny
1. What will you do, If there bea connidenuble difference
i ined value and corredled value, 1
pretlictor corrector methods?
iton ¢ If there is a coraideralle difference betwnen
-eornooted value, We Lake the corrected wale
and find! out the new corrected: value
Jill there i no growl difference betweonWenn AL METHODS TS SCIENCE Arty
nt
‘
2 n®
4 ody
&
+e i ono J Gao" tee
Nt i lnteron oy ody yy
y whee ie
ae
2 Stete Milnes canreetor formula, (eg v7 May,
i iM
Selution : Ser quest 2
20) How mony prior values re required le
7 nae vaies in Milne's method? Prodi iy.
Solution © Four prive valies
W) Piek out the correct answer ;
The error teem in Milne's Pretictor Formula ts
W Sie! ih 19h
a) " A Wh iq Ay a ag Of 4) b
Solution = The error term in tat,
SU.
 
 
 
 
  
  
 
What is the error term in Mil
Solution : The error tern ie
32. Write AN
(Oet 96 MU),
Bharathia;
  
Solution t; WAIT AMD
RENTIAL EQUATION
What is a predictor-corrector method of sealving ®
differential equation? (Oct 97 MUL.
   
 
 
lution = Predictor-correetor
require the values of y at x, ,%
hy
methods are methe
 
14 Rage ne Ot
value of y at x, , 4. We firet use a formula te find
y at x, ) and this is known aa a predictor formula
of ¥ so vot is improved or corrected by another fortress ©
as corrector formula.
26. Say “True or False’ :
dy
Euler's formulas for the solution of a =f %.3
provide a pair of predictor corrector formulas (Nev 95
Bharathidasan Uty)
Solution : The statement is true.
27. Exhibit the Euler formulas for the solution of
a =fix,)) a3 a-pair of predictor corrector farmulas-
Solution : Euler's formula is
yin eset fea yt=t a eee)
Improved Euler's formula i=
'
hb aa
yer evir g | fe ths 1 HV |
 
() is the predictor and (2) is the corrector.
28. Write Milne’s Pp’ ictor corrector formula. (Nov 94
Part time B-E. ; ™ ’s.Uty ; Ap 96, Oct 96 M.U.; Ap 97
Bharathidasan Uty).
Solution : Milne’s predictor formula is
 
where € lies between Xq-gandxy sr
Milne’s corrector formula is4
\) METHODS IN SCIENCE AND ENGG
( G
‘ ANOMER!
# Ay
vain the second interval is computed in
ane the same tour formulas, tiling tha Values
+ of ag Mp respectively
ne place of u
Fil up che blank :
  
x svolve the computation of Fe. Fe
: a _. (Ap 96 Bharathidasa,
Uty
Selution : Caleulation of higher order derivatives of fix,yy,
  
» State the special advantage of Runge-Kutta Method
over Taylor series method. (Nov 95, Ap 97
Bharathidasan Uty ; Ap 96, Oct 96 M.UL).
Solution : Runge-Kutta methods do not require prioz
ot higher derivatives of y (x), as the Taylor method
the differential equations a using in Applications are
sted. the calculation of derivatives may be difficult
the Runge-Kutta formulas involve the computation of
various positions, instead of derivatives anc this
ction occurs in the given equation,
21. Is Euler’s modified formula, a particular case of
second order Runge-Kutta method? (Oct 97 M.U.)
Solution : Yes, Euler's modified fo
second order Runge-Kutta method,
22. Say ‘True or False’ :
   
  
rmula is a particular case of
Modified Euler's method ig the Runge-Kutta method of
second order, (Ap 97 Bharathidasan Uty)
Solution : The statement is true.
23. Compare and cont
Runge-Ku
differen
rast Taylor series method am!
{ta method in solving a first order ordina”Y
tial equation numerically, (Oct 95 M.U.):
Solution + Refer question 20,
2
24. Which is better-Taylor’s method or RK. method
why? (Oct 95 M.U,) ;
Ds
Solutian « ‘Rafise ascectl.
 
_———
TT
wit
pill
Alt thi
vy wnothiodd tie Chel hee ayy y
a ght Mutorertlal Hq UAL LA, ‘Ay
a
situate anette
iy Mt
wi
sanadiann A a EH peiy)
two HE
4 tlie
js cttmivontial eqniallon WP Oy, yp, ‘od iy
Win the
Walia niet tial te
offense ht
Vy og OP ”
uy iti
he written y
Mire can alii
viv thy norte Joe foo
Hh State modified Kuler algoriiiim to salve
VFO volvo tht ig th Oot 0 MAU)
Solution: When vs iy tA, toby ee yy
h Hee
Thom yy yy t a fing wady F099
Me Fill up the blank
The improved Buloy method in based on the avercigen
(Nov 97 MAK,U) ti ith
Solution + Slopes
15. Till up the blank ;
The mottified Ruler method ig bared on the average of
Solution ; Points,
16. Write the Runge. order
, “Kutta al cond
solving y « piy Ys yay) a "— :
(Oot 4 Ny as Tech, M.U)
onote the intery
Vithioy are ( "T betwoon
I) foranutgy 2% tte frat increment in ¥a
ani
  
Then 2
Then 2) = age hwy eye Ay
wom a
The merement is +
eo valae™
T Manner weg
the seoond interval expat
2 th : e samie tires formulas. asthe uy
y we > .
: Re PACS of xy wy Tespectiwedy
 
     
 
“oo
17. State the third erder RK, method algortihm fie
Linterentiol
the numerical solution of the fist order +
equation. (Nov 94 Part time KE. MS.UG?:
 
Solution : To solve the
 
ferential equate *
fe
third erder RK. methad, we use the tollowmg aigormt het
bh =kfie.y)
= &, }
tes fjxt8iy+2
, 2 z
kg th fixe hye Dhy— hy)
and avedty +4828)
1S. Write,down the Runge-Kutta formula of fourth order
to solve St a fr.s) with wine) = Sa
(Ap 96 M.U. ; New 35 MSU:
Ap 95 Part time BE, MS UTy. ; Nev 97 M.K.UO
Solution : Let k denote the interval between equidistant vahies
of x. If the initial values aTe (%).Ng) the first increment mt
is computed from the formulas.
ky HAS %o.20)
: h & )
Ry= hf] 2s +98" 3 |
‘ ky)
aynhe| sot 30707 :
kg=h Fixgth yet a)
and ay= Jer t2has 2b reea
MU Net
MTA,
tlh ltr Chee nk iy. atity
“Wily ‘he ay is aa
Win i
THe Bute) "Wty 4, rele cbifferentiad equa
‘Ap iy HOD tas Wty)
Solution i yi
od Yn VK ft, Ymiin oh) 3.4
Where the VON ity Hential eeopunsdesa ja af
the sa
Given ¥ «xy, 944) “Vind yO 1) hy Butera metho
(Ap 96 Mig)
Solution ; Por the
Alporuthiny in Yen
fia
!
Z Euler
Aifferertial + epaation fi
. | - Mn ¥ Aft, Ym!) 4
Here y et+y. Bo fa, yy rey
Initial condition is x ~O,yelie
Take he 1
* Ing m= 0,9) = ¥94 Wf leg. vo)
From (1), taking SP ia
el+ 1+)
a1-}
§ =
State aiiae on Belew sg vmall, the method ix too sh
10. dd ph 1s nit ;
In Euler's method e ate inaccurate = ty
nd. if h is large, 8 (Ap
ty a
y= 9, 5law VN
De solution af dhediasen amet armenia!
EETev Ad) Dagan td darter
—
ABE SBR ABN ot Ate anniedra tone Het!
peastbal
1 Whata
mt Tee wnentiied aetad tenn shite
| went annie
 
Consider the first onder differential equation oY Pov gde iba
the exact solution vue) of the differential equation ia Che eee
age Sx, be represented by the fill Hine ahower ay the eltaarane
We divide the range «,, — 2 inte a number of stopmizes of weqntaal
length. Ler Sea a. Kya At eWanowdn, Bre Che varia step
Joeations. Fer each xj, approximate valuen of the dependent
variable y() are calenlated using a suitably reeursive foervtatoa
These values. are Yoo ¥1yd2 een Noy and these are shown by
F ‘Let the boundary condition be y (vo) = vo Computation
rox value yy ce My be known as numerical
ae be for the first orde
; "Part time ILE. MESUty)
solution af the equationpods IN
ancap Mere
NI ERI \
3
h he ye AP oy
: io ‘aie Ht
¥ 1 # =“
of ¥ wit x at the poing
Jonotes th th qorivative
denote s
tin) sy gg » Taylor method
ats 4 jemerits of the -
3, Write the ae oe dine 3.6. M.S.Uty $ Oct 96 MU)
ion, (NOY ,
ae main text book.
f the
Taylor series method?,
Bharathidasan Uty)
1 text book,
solu
fer to sy oon page 341.0
sadvant
M.U.) (AP 96
341 of the mait
solution + Re :
i F n
ga. What is the di age I
(Oct 96, Oot v7
Solution + Refer to $7 on page
4. Fill in the blank =
s method will’ BE Very useful to give some
ful ngnerical methods such as Runge Kutta
= method etc. (Ap 95 Bharathidasan Uty).
Solution ¢ initial starting values.
5. Fill up the blank :
  
 
 
 
 
The use solve numerically differential
_ts restricted by the labour involved in the
ie tion of _____» (Ap 96 Bharathidasan Uty).
Solution : higher order derivatives.
6. Write down the fourth order Tayl i
(Noy 97 M.S.Uty). i al
of Taylor sertes t
 
 
 
Solution a ee
elution $y) 4.4 Ym th Ym + Fy nt
™ tere y", denotes the r'” derivative of y warct. x at the poiltof
4 ANT
  
 
VIM Witit wneegntad, 1EBEGAE
mn ; ‘
4 PUES, Bary Mitte nappa megirA tiered
4 Melee ay
“Hera Oo, pi Wn. Ce oe
Vel eObberee Mie peroy : 7
CO) OF inn ee cine ben weeniitet
OH yan ey
Ihe Guy
' NY son de Fo ey ed
Te Bi me tie Hikh= mags fas,5
oy hve MUO ia iW ee WL
HP up the blank
af qualiar
Uhre woh Ntion of the difference ‘ Psa
‘eae ity).
ME Hy 0 4 tty, melt tAp. Khurathidasan Uty
Solution © Whe piven ena con hae verter a
 
UE - 2B 4 tu, bd
The ataib e
¥ tquation in We - 2H +10
he. = 17 © O5(R Wie aye Ba 1,1
So the solution is ie fey eegny lV" = eye eqn
59. Find the solution of the difference equation
4yn,2-4u4,,,+4u, 2". (Nov 97 Bharathidasan Uty).
Solution : The piven equation can be written as
(EB? -4 E+ 4), =2"
The complementary funetion U,, is
(E*-4£+4)U,=0
found such that
The auxiliary equation is B48 + 4-0
ie. (E=2)7 30. E=2,2
2 Uy = (ey enn) 2"
The particular integral v, is
(B°-4 EB +4) 0, =2"
1
Pu aesa
found such thatMERICAL merHops IN SCENT ae ENGg
NUMEBICA” 1
534
: 1 ; 2M
(B-2)°
— gt =a
gn(n-1) os Ph Q
latent 6-1]
2 (E-a)
-9"
Hencg the general solution is
Uy Un +p
2" ?a@a))
=(cy+egn) 2r+ ay
2
60. Firid the particular integral of (E"-7E+12), yn
(Nov 97 M.K.U,).
Solution : The particular integral Uy is found such that
(E?-7 B+ 12) u, =2"
Lia
-7TE+12
ea gn) gr gnt
2-1x2412 2
61. Fill up the blank :
  
Sth =
The particular intergral of the solution of the difference
equation yn49-6y,4,+9y=3" ig (Nov 95
Bharathiar Uty)
Solution : The given equation can be written as
(E°-6£+9)y, =3"
 
The particular integral u, is found such that
(E* -6E+9)u, =3"te vO MIiNAtiy
sh
*. (Noy a7
ny tent book
2) and (3)
ing Aand B in
from (1), (2)
Wey
INT Ry.
DVD a Nat
‘ LN Mitte uxegeiay INTERVALS, st
Me Yeap i NTE prey FQUATIONS
: ¥ on ‘
yao mened “4+ ¥, (20 ~ 80) « O
ory va 1804, 66
wYnag=Bpy : _
bo, saat Hy, 0
Form the
and § from
Oct 96 atts
Solution t
tifferenoe equation by eliminating
the relution Yn a2 he 2)": Oct 95 ,
SiN Some ate an cy
Vabite
 
 
vel
'
Book. «
O36 (oop et)
and Yeeg=a Eb imeee
“AaB sdb (- 2 iy
i (uhtities a 2" and 6 (—2y" from (1), (2
Y using determinants, The result is
[esq 4! 4
Yui 2 |=0
Me tt
We can eliminate the
and (3), b
 
UP Sag 2(2+3)
Le. dy, po- 16 y, = ory, vocdy,
51. Solve y, , 9- 8yy.1415y,=0 (Nov 94 Part time B.E. ;
MS.Uty )
Solution : Refor worked Ex. 3 on page 312 of the main text
book,
52. Solve y, ,o-4y,=0. (Ap 95 Part time BEL; MS.Uty)
 
Solution : The given equation can be written as
(B°- dy, =0. -
The auxiliary equation is E°
 
fai)». es
ie(B-2)(E+2)=0 8s -2,2. Ba .
So the solution.is 4 =C)-2"+Cy (-2)" where Ce
arbitrary constants, :peo IN ATIC a
‘ i ANn
aa pcrtlev kWe,
ieee My,
Ne Rey VOOM
capeabiede Can dhe
Soltis Whe in Wr tte,
4
wi \ u
tho anxitine. equation a” GW Bie
hin’ Nh =e Real
, (BO a Where Goa
tha Ohat RON 1a By 1 rey ra
HEU CU EY comtetin be
Sa. Dick up the correct answer t
The solution of the difference equation UE" — 5 BG) Hy 0 iy
Mey enya! WC eeyms" ey Cy, an + (9!
Od) Ce eas
 
" a) C) (<2) 4gt= ay"
(Ap 95 Bharathidasan Uty)
Solution : The auxiliary equation is R®-5 846 0
ie (R-2) (8 -3)20).0.8 Bde
Sethe solution ivy, Cy 2" 409 3"
 
or False’ ;
The solution of ¥¢ 44 Mea pty =O is
2nx
TX sR sin
y= Acos ?®
(April 95 Bharathidasan Uty ; Ap 96 MU)
Solution : Refer worked Ex on page 313 ain text
book. Tho statement is correct, ae . eo
56. Fill in the blank ;
If ati Pare the roo
ts af the auxiliary equation of
difference equation, then th Bree
¢ complementary function is ——
(Ap 95 Bharathidasan Ut!
Solution : :
CF. i¢ =r (Cos. x 0+ Cysin x @)
where Te eaneea tae
5: oQ & A~ INTERPOLATION w
527
DIVIDED, NUM,
a TH UNEQUAL INTERVALS,
' INTE. DIFFE, EQUATIONS
This i * known a8 the general Gauss - Lagendre integration
formula. For derivation refer to page 304 of the main text book
Putting n=1 and omitting g i es in the
shite WH g Second and hyper difference’
a
, .
J+fyda=} ifaysfoshi)=h +9
which is the trapezoidal rule, (For details, refer to page 394)-
37(b). How is Simpson's one third rule a special c@8¢ of
Newton Cotes quadrature formula?
Solution + See deduction 2 on page 304 of the main text book-
37(c). Establish Simpson's three eighths rule.
Solution : Putting n=3 and omitting fourth and hyper
differences in the above Newton-cotes formula, we get
a+3h
J ydx=3h 1+
GA, 3x3 2, 3 3
27 go tao jo
3 3 2,147.1)
wan) 14pe-ns fe +g@-) jr
28h (1s38+3E +E fo)
=8Ai p+3fe+n+afas2h)+f(ar Shy)
=} (nt8n+301% )
Similarly
a+6h
J ydseSb (urdyst 83u*9)
ardh
a+bh
J ydan 5 (I-24 8% -14 8964 I0 <1)
atin- 3A
Adding all auch expressions from a toa+nh=,
when n is a multiple of 3, we get‘w
BIS NUMERICAL METHODS IN SCIENC vGG.
nal
A [(xy=0
Bp My
f&) hth
tina. en a a) (xg — 0p) + Ot — Fn)
(x =x) 8 ay) oe 4) OO x) (Xo ~*1 07 *n
fx) ey
ee
(py —X) (y — X0) os On Fn v
(Refer result of question (2) on page 513)
fy ted +
* ax) &—Xy) Hq) 70) (xg- £1) »-- @o-%n)
‘ fn)
ee
* @—a,) &p— 20) 2 Hn Fn - vd
Multiplying throughout by (*-*0) (x- x1) -@— Xn) We get
(x — 3) (&— 49) (x=*n)
__@- 4) e-
fa)= ==) GSE ao
A yscoovassasnsinotesane SP esunarnensonsqseseenee
2 (x — 29) (% — 41) ++ @~%n- »
(Gq —%0) Gn 41) + On Fn - v
fp)
This is clearly Lagrange’s interpolation formula.
16. Explain the difference between Newton’s divided
difference formula and Lagrange’s interpolation
formula. (Ap 97 Bharathidasan Uty).
Solution : Lagrange’s interpolation formula is merely a variant
of Newton's divided difference formula. This is fully proved in
question 15. : =
17, What is ‘inverse interpolation’?
Solution : Suppose we are given a table of values of x andy.
Direct interpolation is the process of finding the values of y
corresponding to a value of x, not present in the table. Inverse
interpolation is the process of finding the values of *
corresponding to a value of y, not present he table.Qk a_
INty
DIVIpy: ERPOL jr
ED, yy, ATION
Ss ) NUM gh Wet “a
18. Give the j M. & Ip DntBtIAL INTEMIAS a
Nive, PE RQUATIONS
(Nov 97 iM Veree of ty MIATION
S.Utyy MRT anKe's interpolation formula.
Solution :
z=Y-y)iy~yy i
Oo-y) Grd
IDO -y,). (vo aa ay
yi
20) Y= Hg) 1s Fn)
YO) 1 = Yn) os 1 —Ynd
  
On =o) Wn =)» On In -1)
19, Wh
im has Lagrange’s formula over
+
Sn
= : See question 11. In addition to the advantage
men ioned there, Lagrange’s formula can be used for inverse
interpolation also, while Newton’s formulae cannot be used.
20. State Newton’s formula to find f’(x) using the
forward differences (Oct 95 M.U.).
Solution : Let y=f(x) be a function
Yor ¥1 In corresponding to %9,%1,---*n
Let the values of x be at equidistant interval:
taking the values
of the independent
variable x. s of
size h.
y 12:3
Then
2p-1 3p" - 6p +2) 3
panes} soe Esher HS
x-X9
where P=}, (1)
j di chi .
(a) gi the value of at any x, Which is a non tabular value.
: Pages =0, Then putting p =0 in (D, we have
‘icular, at 7-702 =° pm
In particul ; :
2
wv) “peyet| an-Sanr tn |
dz j20vox IN SCIENCE AND ENGGIE
grt
+i re oo OIE
ayes * + ya]
eahths rule
$m, What te the order OF cere’ in Trapezoidal formata
ihe Traperondal formula is of the
This i= Sunpsan’: Thee
Solution ¢ Error in
h
49, What is the order of error in Simpson's
er OT MAL; Ap 97 Bharathidasan tty)
Selution ; Error « the Simpson formula is of the ord
40. State the local errer term in Simpson's
rule, (AP 97 Bharathidasan Uty)
Solution : Principal part of the error an the int
where vy; is the value of yand yf | the
denvative of vata sexy
41. What is the local error term in T,
Solution : Principal part of the error |
 
where 9, 48 the value of y and yy 1a
derwative of yatasay
iideperdent varvable x,
dilterences af the a
Examples)! a, <Qe 4 Ln
NTE;
Diving e POLATION yy
TDED, NUy TION WITH UNEQUAL INTERVALS
What adva © INTE, DIFFS. EQUATIONS
New n
= wtGn? tage has Lagrange’s formul
 
ii,
a over
Soluti
‘olution ; 7
Newton mee forw,
Variable x i
x are
ard and backward interpolation formulae of
© Use
ts eu only when the values of the independent
E dependent ¥ HY spaced can also when the differences of
-lgrange’s interncanna y become smaller ultimately. But
of x, the indepe ee formula can be used whether the values
whether the fe lent variable are equally spaced or not and
erence of y become smaller or not.
ay ‘True or False’ :
To fing
find the inte ‘ :
Ordre : 3 he inte rpolating polynomi
~» Lagrange’s method
when the e, ;
en the x's are not equally spaced.
 
12, §,
‘al for the given data
can be applied only
  
(Nov 95 Bharathidasan Uty)
Solution : The statement is false. ;
13, What is the disadvantage in practice in ap,
_-~” Lagrange’s interpolation formula?
plying
Solution ; Though Lagrange’s formula is simple and easy to
remember, its application is not speedy. It requires close
attention to sign and there is always a chance of committing
some error due to a number of positive and negative signs in
the numerator and the denominator.
14. Say ‘True or False’ :
fange’s interpolation formula can be used for equal
intervals. (Ap 95 Bharathidasan Uty)
Solution : The statement is true.
15. Show that Lagrange’s interpolation formula is merely
a variant of Newton’s divided difference
formula.
Jution : Let feo) sf ep Fn) be the values of fix)
corresponding to the arguments Xp ,X) ,--4n- If f(x) is a
its (n+ Dthe divided differences will be
polynomial of Jre®{ @Q@ ™
" 5 INTERIOLATION Writ tiNKQUAL ITERN a“
VIDED NUM & INTE inbEE KQUATIONS
Fe Anaya YO Pity ay he tag ae ito oe
YAR = tal ty YD = wy hf org, tye tg to
' ' ‘
TUR Ri) 0 a9) cass 0 — a EN
TA i) OR Dy TDP ta De fa od
I the funet the in + 198
( fon fo) in a polynomial of degree fy
divided din
“ronee will be zere
R : 0
So the list term in CD) ie. fe stg tbs ma
Hence (1 bees on
PW) © flay) ata Xo) f(x 44) 4 = xy) OF a FO ha eat
ry) Cr
om 100 ay ay) ty fe
The formula (2) is called Newton's dtorded difference
titerpolation formula.
7. Say ‘True ¢
 
Falne' :
Newton's divided difference formula is applicable only for
equally spaced intervals, (Ap 97 Bharathidasan Uty)
Solution : The statement is false,
8 Find the second degree polynomial fitting the
following data: (Ap 96 M.U,)
a 1 2 4
i 4 5 13
Solution : The divided difference table is as follows
x Ve AY, A” ¥,
l 4
hed
2-1"!
¢ 4&8 aha
4-1"
hh
Berea 4
4 13
N '4 divided difference interpolation formula isant NUMERICAL METHODS IN SCIENCE AND BNGG.
Ry
 
5H. When will iteration method suce
 
Soluti
     
AUy,
Ry i® the fang Yittteny,
tn ondor that the iteyation’ may succeed, enpation of Ry i the tig ORR: As
        
 
 
    
    
  
 
 
   
7
i a ate eee i Heal sap H pA Ry inereaag§ ea Mossad teny
the others in that equation) and the 7 ew
attached to a different unknown in that ation. This fe Voy
ok Cent will be got when the large coefficients are along Ro incresgeg nil nh ah Owe
the leading diagonal of the matrix of the ene ts. t “Rady
i
57, Explain relaxation method to solve a system of ate 0d ee »
simultaneous ns. (Ap 96 M.U.) rade ina ME tig
Salution : Refer §8 page 147 of the main text book, cach stayy MPa ge My et ES With sere
58 Write down the relaxation table for the solution of ‘The actual the acta ys in th ae Seed tae
the system x+2y B,2x+ 25 y= 15. ual Telatation Ate nee at
(Ap 97 Bharathidasan Uty), . i§ shown in the floning table
x lerwing table
Solution : The residuals ry, ry are given by y F
0 ee 8
ryex42y43 ‘ C  %
2x4 By 15 i Tag
at
‘The operation table | 0
ts Y Te ea
Explanation : (1) Ling j f
RO «(see calculating r),r», (1) is obtained by taking s-0=y and
R, 0 D @ (2) The r
: i wuidate thi ly largest residual is rp(=-9). We try to
59. Solve the equations 10x-2y=8, -*+10y=9 by the Viquidate this by applying a eae ye or
relaxation method. (May 97 Anna Uty). we apply 1-Rp, From . bya ie ted
Solution + The residuals ry, rp are given by , ~2, tory ry respestivaly ond 0, 1 to the values of
x and y respectively. Line |
ry=1x-2y-8 tent, (2 gives the current values of x,y and
ry=-x+1y-9 } (3) The muimer anion ints ts
We have the operation table : | this we apply 1-2, From the operation table, we fd that his
adds 10, -1tory,7 respestively and 1, 0 to the values:
wee AS seandy respective. Line (3) gives current values of 5,7 and
Rk, 1 i at ' the residuals,
R 0 4 =2 20
As the residuals ‘pre 2ere, we get the exact solution: on
x=l=y. ezt | act
| ,