Page 1
Edurev123
3. Interpolation
3.1 Using Lagrange interpolation formula, calculate the value of ?? (?? ) from the
following table of values of ?? and ?? (?? ) :
(2009 : 15 Marks)
Solution:
Usually Lagrange interpolation formula, first we will form the equation of ?? (?? ) . Now, as
per the formula,
?? (?? )=
(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 0
)
(?? 0
-?? 1
)(?? 0
-?? 2
)(?? 0
-?? 3
)(?? 0
-?? 4
)(?? 0
-?? 5
)
?+
(?? -?? 0
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 1
)
(?? 1
-?? 0
)(?? 1
-?? 2
)(?? 1
-?? 3
)(?? 1
-?? 4
)(?? 1
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 2
)
(?? 2
-?? 0
)(?? 2
-?? 1
)(?? 2
-?? 3
)(?? 2
-?? 4
)(?? 2
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 4
)(?? -?? 5
)?? (?? 3
)
(?? 3
-?? 0
)(?? 3
-?? 1
)(?? 3
-?? 2
)(?? 3
-?? 4
)(?? 3
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 5
)?? (?? 4
)
(?? 4
-?? 0
)(?? 4
-?? 1
)(?? 4
-?? 2
)(?? 4
-?? 3
)(?? 4
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)?? (?? 5
)
(?? 5
-?? 0
)(?? 5
-?? 1
)(?? 5
-?? 2
)(?? 5
-?? 3
)(?? 5
-?? 4
)
Now, ?? 0
=0,?? 1
=1,?? 2
=2,?? 3
=4,?? 4
=5,?? 5
=6 and ?? (?? 0
)=1,?? (?? 1
)=14,?? (?? 2
)=
15,?? (?? 3
)=5,?? (?? 4
)=6, ?? (?? 5
)=19.
So,
Now,
Page 2
Edurev123
3. Interpolation
3.1 Using Lagrange interpolation formula, calculate the value of ?? (?? ) from the
following table of values of ?? and ?? (?? ) :
(2009 : 15 Marks)
Solution:
Usually Lagrange interpolation formula, first we will form the equation of ?? (?? ) . Now, as
per the formula,
?? (?? )=
(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 0
)
(?? 0
-?? 1
)(?? 0
-?? 2
)(?? 0
-?? 3
)(?? 0
-?? 4
)(?? 0
-?? 5
)
?+
(?? -?? 0
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 1
)
(?? 1
-?? 0
)(?? 1
-?? 2
)(?? 1
-?? 3
)(?? 1
-?? 4
)(?? 1
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 2
)
(?? 2
-?? 0
)(?? 2
-?? 1
)(?? 2
-?? 3
)(?? 2
-?? 4
)(?? 2
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 4
)(?? -?? 5
)?? (?? 3
)
(?? 3
-?? 0
)(?? 3
-?? 1
)(?? 3
-?? 2
)(?? 3
-?? 4
)(?? 3
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 5
)?? (?? 4
)
(?? 4
-?? 0
)(?? 4
-?? 1
)(?? 4
-?? 2
)(?? 4
-?? 3
)(?? 4
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)?? (?? 5
)
(?? 5
-?? 0
)(?? 5
-?? 1
)(?? 5
-?? 2
)(?? 5
-?? 3
)(?? 5
-?? 4
)
Now, ?? 0
=0,?? 1
=1,?? 2
=2,?? 3
=4,?? 4
=5,?? 5
=6 and ?? (?? 0
)=1,?? (?? 1
)=14,?? (?? 2
)=
15,?? (?? 3
)=5,?? (?? 4
)=6, ?? (?? 5
)=19.
So,
Now,
?? (?? )=
(?? -1)(?? -2)(?? -4)(?? -5)(?? -6)×1
(0-1)(0-2)(0-4)(0-5)(0-6)
?+
(?? -0)(?? -2)(?? -4)(?? -5)(?? -6)×14
(1-0)(1-2)(1-4)(1-5)(1-6)
?+
(?? -0)(?? -1)(?? -4)(?? -5)(?? -6)×15
(2-0)(2-1)(2-4)(2-5)(2-6)
?+
(?? -0)(?? -1)(?? -2)(?? -5)(?? -6)×5
(4-0)(4-1)(4-2)(4-5)(4-6)
?+
(?? -0)(?? -1)(?? -2)(?? -4)(?? -6)×6
(5-0)(5-1)(5-2)(5-4)(5-6)
?+
(?? -0)(?? -1)(?? -2)(?? -4)(?? -5)×19
(6-0)(6-1)(6-2)(6-4)(6-5)
(3-1)(3-2)(3-4)(3-5)(3-6)
-1×-2×-4×-5×-6
?+
(3-0)(3-2)(3-4)(3-5)(3-6)×14
1×(-1)×(-3)(-4)(-5)
?+
(3-0)(3-1)(3-4)(3-5)(3-6)×15
2×1×(-2)(-3)(-4)
?+
(3-0)(3-1)(3-2)(3-5)(3-6)×5
4×3×2×(-1)(-2)
?+
(3-1)(3-2)(3-4)(3-6)×6
5×4×3×1×(-1)
?+
(3-0)(3-1)(3-2)(3-4)(3-5)×19
6×5×4×2×1
?+
2×1×(+1)×(-2)×(-3)
2×4×5×(+6)
+
3×1×(-1)×(+2)×(-3)×14
1×3×4×5
?+
3×2×1×(-1)(-3)×6
5×4×3×(-1)
+
3×2×1×(-1)×(-2)×19
6×5×4×2
=
1
20
-
21
5
+
45
4
+
15
4
-
9
5
+
19
20
=
1-84+180+75-36+19
20
=
275-120
20
=
155
20
=
31
4
?? =
31
4
3.2 Find the value of ?? (?? .?? ) using Runge-Kutta fourth order method with step size
?? =?? .?? from the initial value problem.
?? '
?=????
?? (?? )?=??
(2009: 15 marks)
Solution:
Page 3
Edurev123
3. Interpolation
3.1 Using Lagrange interpolation formula, calculate the value of ?? (?? ) from the
following table of values of ?? and ?? (?? ) :
(2009 : 15 Marks)
Solution:
Usually Lagrange interpolation formula, first we will form the equation of ?? (?? ) . Now, as
per the formula,
?? (?? )=
(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 0
)
(?? 0
-?? 1
)(?? 0
-?? 2
)(?? 0
-?? 3
)(?? 0
-?? 4
)(?? 0
-?? 5
)
?+
(?? -?? 0
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 1
)
(?? 1
-?? 0
)(?? 1
-?? 2
)(?? 1
-?? 3
)(?? 1
-?? 4
)(?? 1
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 2
)
(?? 2
-?? 0
)(?? 2
-?? 1
)(?? 2
-?? 3
)(?? 2
-?? 4
)(?? 2
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 4
)(?? -?? 5
)?? (?? 3
)
(?? 3
-?? 0
)(?? 3
-?? 1
)(?? 3
-?? 2
)(?? 3
-?? 4
)(?? 3
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 5
)?? (?? 4
)
(?? 4
-?? 0
)(?? 4
-?? 1
)(?? 4
-?? 2
)(?? 4
-?? 3
)(?? 4
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)?? (?? 5
)
(?? 5
-?? 0
)(?? 5
-?? 1
)(?? 5
-?? 2
)(?? 5
-?? 3
)(?? 5
-?? 4
)
Now, ?? 0
=0,?? 1
=1,?? 2
=2,?? 3
=4,?? 4
=5,?? 5
=6 and ?? (?? 0
)=1,?? (?? 1
)=14,?? (?? 2
)=
15,?? (?? 3
)=5,?? (?? 4
)=6, ?? (?? 5
)=19.
So,
Now,
?? (?? )=
(?? -1)(?? -2)(?? -4)(?? -5)(?? -6)×1
(0-1)(0-2)(0-4)(0-5)(0-6)
?+
(?? -0)(?? -2)(?? -4)(?? -5)(?? -6)×14
(1-0)(1-2)(1-4)(1-5)(1-6)
?+
(?? -0)(?? -1)(?? -4)(?? -5)(?? -6)×15
(2-0)(2-1)(2-4)(2-5)(2-6)
?+
(?? -0)(?? -1)(?? -2)(?? -5)(?? -6)×5
(4-0)(4-1)(4-2)(4-5)(4-6)
?+
(?? -0)(?? -1)(?? -2)(?? -4)(?? -6)×6
(5-0)(5-1)(5-2)(5-4)(5-6)
?+
(?? -0)(?? -1)(?? -2)(?? -4)(?? -5)×19
(6-0)(6-1)(6-2)(6-4)(6-5)
(3-1)(3-2)(3-4)(3-5)(3-6)
-1×-2×-4×-5×-6
?+
(3-0)(3-2)(3-4)(3-5)(3-6)×14
1×(-1)×(-3)(-4)(-5)
?+
(3-0)(3-1)(3-4)(3-5)(3-6)×15
2×1×(-2)(-3)(-4)
?+
(3-0)(3-1)(3-2)(3-5)(3-6)×5
4×3×2×(-1)(-2)
?+
(3-1)(3-2)(3-4)(3-6)×6
5×4×3×1×(-1)
?+
(3-0)(3-1)(3-2)(3-4)(3-5)×19
6×5×4×2×1
?+
2×1×(+1)×(-2)×(-3)
2×4×5×(+6)
+
3×1×(-1)×(+2)×(-3)×14
1×3×4×5
?+
3×2×1×(-1)(-3)×6
5×4×3×(-1)
+
3×2×1×(-1)×(-2)×19
6×5×4×2
=
1
20
-
21
5
+
45
4
+
15
4
-
9
5
+
19
20
=
1-84+180+75-36+19
20
=
275-120
20
=
155
20
=
31
4
?? =
31
4
3.2 Find the value of ?? (?? .?? ) using Runge-Kutta fourth order method with step size
?? =?? .?? from the initial value problem.
?? '
?=????
?? (?? )?=??
(2009: 15 marks)
Solution:
As per Runge-Kutta forth order method,
?? 1
=h?? (?? 0
,?? 0
)
?? 2
=h?? (?? 0
+
h
2
,?? 0
+
?? 1
2
)
?? 3
=h?? (?? 0
+
h
2
,?? 0
+
?? 2
2
)
?? 4
=h?? (?? 0
+h,?? 0
+?? 3
)
?? =
1
6
(?? 1
+2?? 2
+2?? 3
+?? 4
)
and next ?? will be
?? 1
=?? 0
+?? ?????????
and ?? (?? ,?? )=?? '
?????????
Here ?? (?? ,?? )=???? ?????????
Now, as per the given problem
?? 0
?=?? (1)=2
?? '
?=?? (?? ,?? )=????
h?=0.2
?? 1
?=h?? (?? 0
,?? 0
)
?=0.2?? (1,2)
?=0.2×1×2=0.4
?? 2
?=h?? (?? 0
+
h
2
,?? 0
+
?? 1
2
)
Page 4
Edurev123
3. Interpolation
3.1 Using Lagrange interpolation formula, calculate the value of ?? (?? ) from the
following table of values of ?? and ?? (?? ) :
(2009 : 15 Marks)
Solution:
Usually Lagrange interpolation formula, first we will form the equation of ?? (?? ) . Now, as
per the formula,
?? (?? )=
(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 0
)
(?? 0
-?? 1
)(?? 0
-?? 2
)(?? 0
-?? 3
)(?? 0
-?? 4
)(?? 0
-?? 5
)
?+
(?? -?? 0
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 1
)
(?? 1
-?? 0
)(?? 1
-?? 2
)(?? 1
-?? 3
)(?? 1
-?? 4
)(?? 1
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 2
)
(?? 2
-?? 0
)(?? 2
-?? 1
)(?? 2
-?? 3
)(?? 2
-?? 4
)(?? 2
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 4
)(?? -?? 5
)?? (?? 3
)
(?? 3
-?? 0
)(?? 3
-?? 1
)(?? 3
-?? 2
)(?? 3
-?? 4
)(?? 3
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 5
)?? (?? 4
)
(?? 4
-?? 0
)(?? 4
-?? 1
)(?? 4
-?? 2
)(?? 4
-?? 3
)(?? 4
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)?? (?? 5
)
(?? 5
-?? 0
)(?? 5
-?? 1
)(?? 5
-?? 2
)(?? 5
-?? 3
)(?? 5
-?? 4
)
Now, ?? 0
=0,?? 1
=1,?? 2
=2,?? 3
=4,?? 4
=5,?? 5
=6 and ?? (?? 0
)=1,?? (?? 1
)=14,?? (?? 2
)=
15,?? (?? 3
)=5,?? (?? 4
)=6, ?? (?? 5
)=19.
So,
Now,
?? (?? )=
(?? -1)(?? -2)(?? -4)(?? -5)(?? -6)×1
(0-1)(0-2)(0-4)(0-5)(0-6)
?+
(?? -0)(?? -2)(?? -4)(?? -5)(?? -6)×14
(1-0)(1-2)(1-4)(1-5)(1-6)
?+
(?? -0)(?? -1)(?? -4)(?? -5)(?? -6)×15
(2-0)(2-1)(2-4)(2-5)(2-6)
?+
(?? -0)(?? -1)(?? -2)(?? -5)(?? -6)×5
(4-0)(4-1)(4-2)(4-5)(4-6)
?+
(?? -0)(?? -1)(?? -2)(?? -4)(?? -6)×6
(5-0)(5-1)(5-2)(5-4)(5-6)
?+
(?? -0)(?? -1)(?? -2)(?? -4)(?? -5)×19
(6-0)(6-1)(6-2)(6-4)(6-5)
(3-1)(3-2)(3-4)(3-5)(3-6)
-1×-2×-4×-5×-6
?+
(3-0)(3-2)(3-4)(3-5)(3-6)×14
1×(-1)×(-3)(-4)(-5)
?+
(3-0)(3-1)(3-4)(3-5)(3-6)×15
2×1×(-2)(-3)(-4)
?+
(3-0)(3-1)(3-2)(3-5)(3-6)×5
4×3×2×(-1)(-2)
?+
(3-1)(3-2)(3-4)(3-6)×6
5×4×3×1×(-1)
?+
(3-0)(3-1)(3-2)(3-4)(3-5)×19
6×5×4×2×1
?+
2×1×(+1)×(-2)×(-3)
2×4×5×(+6)
+
3×1×(-1)×(+2)×(-3)×14
1×3×4×5
?+
3×2×1×(-1)(-3)×6
5×4×3×(-1)
+
3×2×1×(-1)×(-2)×19
6×5×4×2
=
1
20
-
21
5
+
45
4
+
15
4
-
9
5
+
19
20
=
1-84+180+75-36+19
20
=
275-120
20
=
155
20
=
31
4
?? =
31
4
3.2 Find the value of ?? (?? .?? ) using Runge-Kutta fourth order method with step size
?? =?? .?? from the initial value problem.
?? '
?=????
?? (?? )?=??
(2009: 15 marks)
Solution:
As per Runge-Kutta forth order method,
?? 1
=h?? (?? 0
,?? 0
)
?? 2
=h?? (?? 0
+
h
2
,?? 0
+
?? 1
2
)
?? 3
=h?? (?? 0
+
h
2
,?? 0
+
?? 2
2
)
?? 4
=h?? (?? 0
+h,?? 0
+?? 3
)
?? =
1
6
(?? 1
+2?? 2
+2?? 3
+?? 4
)
and next ?? will be
?? 1
=?? 0
+?? ?????????
and ?? (?? ,?? )=?? '
?????????
Here ?? (?? ,?? )=???? ?????????
Now, as per the given problem
?? 0
?=?? (1)=2
?? '
?=?? (?? ,?? )=????
h?=0.2
?? 1
?=h?? (?? 0
,?? 0
)
?=0.2?? (1,2)
?=0.2×1×2=0.4
?? 2
?=h?? (?? 0
+
h
2
,?? 0
+
?? 1
2
)
?=0.2?? (1+
0.2
2
,2+
0.4
2
)
?=0.2?? (1.1,2.2)
?=0.2×1.1×2.2=0.484
?? 3
=h?? (?? 0
+
h
2
,?? 0
+
?? 2
2
)
?=0.2?? (1+
0.2
2
,2+
0.484
2
)
?=0.2?? (1.1,2.242)
?=0.2×1.1×2.242
?=0.49324
?? 4
=h?? (?? 0
+h,?? 0
+?? 3
)
?=0.2?? (1+0.2,2+0.49324)
?=0.2?? (1.2,2.49324)
?=0.2×1.2×2.49324
?=0.598
?? 1
=
1
6
(?? 1
+2?? 2
+2?? 3
+?? 4
)
?=
1
6
(0.4+2(0.484)+2(0.49324)+0.598)
So,
?=
1
6
(0.4+0.968+0.98648+0.598)
?=
2.95248
6
=0.49208
??? f(1.2)=2+0.49208
3.3 Find
????
????
at ?? =?? .?? from the following data :
Solution:
We will use Newton Forward interpolation formula.
The table of finite differences is given by:
Page 5
Edurev123
3. Interpolation
3.1 Using Lagrange interpolation formula, calculate the value of ?? (?? ) from the
following table of values of ?? and ?? (?? ) :
(2009 : 15 Marks)
Solution:
Usually Lagrange interpolation formula, first we will form the equation of ?? (?? ) . Now, as
per the formula,
?? (?? )=
(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 0
)
(?? 0
-?? 1
)(?? 0
-?? 2
)(?? 0
-?? 3
)(?? 0
-?? 4
)(?? 0
-?? 5
)
?+
(?? -?? 0
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 1
)
(?? 1
-?? 0
)(?? 1
-?? 2
)(?? 1
-?? 3
)(?? 1
-?? 4
)(?? 1
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 3
)(?? -?? 4
)(?? -?? 5
)?? (?? 2
)
(?? 2
-?? 0
)(?? 2
-?? 1
)(?? 2
-?? 3
)(?? 2
-?? 4
)(?? 2
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 4
)(?? -?? 5
)?? (?? 3
)
(?? 3
-?? 0
)(?? 3
-?? 1
)(?? 3
-?? 2
)(?? 3
-?? 4
)(?? 3
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 5
)?? (?? 4
)
(?? 4
-?? 0
)(?? 4
-?? 1
)(?? 4
-?? 2
)(?? 4
-?? 3
)(?? 4
-?? 5
)
?+
(?? -?? 0
)(?? -?? 1
)(?? -?? 2
)(?? -?? 3
)(?? -?? 4
)?? (?? 5
)
(?? 5
-?? 0
)(?? 5
-?? 1
)(?? 5
-?? 2
)(?? 5
-?? 3
)(?? 5
-?? 4
)
Now, ?? 0
=0,?? 1
=1,?? 2
=2,?? 3
=4,?? 4
=5,?? 5
=6 and ?? (?? 0
)=1,?? (?? 1
)=14,?? (?? 2
)=
15,?? (?? 3
)=5,?? (?? 4
)=6, ?? (?? 5
)=19.
So,
Now,
?? (?? )=
(?? -1)(?? -2)(?? -4)(?? -5)(?? -6)×1
(0-1)(0-2)(0-4)(0-5)(0-6)
?+
(?? -0)(?? -2)(?? -4)(?? -5)(?? -6)×14
(1-0)(1-2)(1-4)(1-5)(1-6)
?+
(?? -0)(?? -1)(?? -4)(?? -5)(?? -6)×15
(2-0)(2-1)(2-4)(2-5)(2-6)
?+
(?? -0)(?? -1)(?? -2)(?? -5)(?? -6)×5
(4-0)(4-1)(4-2)(4-5)(4-6)
?+
(?? -0)(?? -1)(?? -2)(?? -4)(?? -6)×6
(5-0)(5-1)(5-2)(5-4)(5-6)
?+
(?? -0)(?? -1)(?? -2)(?? -4)(?? -5)×19
(6-0)(6-1)(6-2)(6-4)(6-5)
(3-1)(3-2)(3-4)(3-5)(3-6)
-1×-2×-4×-5×-6
?+
(3-0)(3-2)(3-4)(3-5)(3-6)×14
1×(-1)×(-3)(-4)(-5)
?+
(3-0)(3-1)(3-4)(3-5)(3-6)×15
2×1×(-2)(-3)(-4)
?+
(3-0)(3-1)(3-2)(3-5)(3-6)×5
4×3×2×(-1)(-2)
?+
(3-1)(3-2)(3-4)(3-6)×6
5×4×3×1×(-1)
?+
(3-0)(3-1)(3-2)(3-4)(3-5)×19
6×5×4×2×1
?+
2×1×(+1)×(-2)×(-3)
2×4×5×(+6)
+
3×1×(-1)×(+2)×(-3)×14
1×3×4×5
?+
3×2×1×(-1)(-3)×6
5×4×3×(-1)
+
3×2×1×(-1)×(-2)×19
6×5×4×2
=
1
20
-
21
5
+
45
4
+
15
4
-
9
5
+
19
20
=
1-84+180+75-36+19
20
=
275-120
20
=
155
20
=
31
4
?? =
31
4
3.2 Find the value of ?? (?? .?? ) using Runge-Kutta fourth order method with step size
?? =?? .?? from the initial value problem.
?? '
?=????
?? (?? )?=??
(2009: 15 marks)
Solution:
As per Runge-Kutta forth order method,
?? 1
=h?? (?? 0
,?? 0
)
?? 2
=h?? (?? 0
+
h
2
,?? 0
+
?? 1
2
)
?? 3
=h?? (?? 0
+
h
2
,?? 0
+
?? 2
2
)
?? 4
=h?? (?? 0
+h,?? 0
+?? 3
)
?? =
1
6
(?? 1
+2?? 2
+2?? 3
+?? 4
)
and next ?? will be
?? 1
=?? 0
+?? ?????????
and ?? (?? ,?? )=?? '
?????????
Here ?? (?? ,?? )=???? ?????????
Now, as per the given problem
?? 0
?=?? (1)=2
?? '
?=?? (?? ,?? )=????
h?=0.2
?? 1
?=h?? (?? 0
,?? 0
)
?=0.2?? (1,2)
?=0.2×1×2=0.4
?? 2
?=h?? (?? 0
+
h
2
,?? 0
+
?? 1
2
)
?=0.2?? (1+
0.2
2
,2+
0.4
2
)
?=0.2?? (1.1,2.2)
?=0.2×1.1×2.2=0.484
?? 3
=h?? (?? 0
+
h
2
,?? 0
+
?? 2
2
)
?=0.2?? (1+
0.2
2
,2+
0.484
2
)
?=0.2?? (1.1,2.242)
?=0.2×1.1×2.242
?=0.49324
?? 4
=h?? (?? 0
+h,?? 0
+?? 3
)
?=0.2?? (1+0.2,2+0.49324)
?=0.2?? (1.2,2.49324)
?=0.2×1.2×2.49324
?=0.598
?? 1
=
1
6
(?? 1
+2?? 2
+2?? 3
+?? 4
)
?=
1
6
(0.4+2(0.484)+2(0.49324)+0.598)
So,
?=
1
6
(0.4+0.968+0.98648+0.598)
?=
2.95248
6
=0.49208
??? f(1.2)=2+0.49208
3.3 Find
????
????
at ?? =?? .?? from the following data :
Solution:
We will use Newton Forward interpolation formula.
The table of finite differences is given by:
By Newton Forward interpolation formula, we have
?? (?? +?? h)=?? (?? )+?????? (?? )+
?? (?? -1)
2!
?
2
?? (?? )+
?? (?? -1)(?? -2)
3!
?? 3
?? (?? )+?. (??)
Here, ?? =0.1,h=0.1
??????????????????????????????? =
?? -?? h
=
?? -0.1
0.1
? from (i),
?? (?? )=0.9975+
(?? -0.1)
0.1
·(-0.0075)+
(?? -0.1)
0.1
·(
?? -0.1
0.1
-1)·
1
2
·(-0.0049)
?+(
?? -0.1
0.1
)(
?? -0.1
0.1
-1)(
?? -0.1
0.1
-2)·
1
6
(0.0001)
???? =?? (?? )=0.9975+
(?? -0.1)
0.1
·(-0.0075)+
(?? -0.1)
0.1
(
?? -0.2
0.1
)·
1
2
(-0.0049)
?+
(?? -0.1)
0.1
·
(?? -0.2)
0.1
·
(?? -0.3)
0.1
·
1
6
(0.0001)
??
????
????
=
1
0.1
(-0.0075)+
1
0.1
(
?? -0.2
0.1
)·
1
2
(-0.0049)+
(?? -0.1)
0.1
·
1
0.1
·
1
2
(-0.0049)
?+
(3?? 2
-1.2?? -0.07)
6×(0.1)
3
·(0.0001)
??
?? '
?? ????
(?????? =0.1)=?-
0.0075
0.1
+
(-0.1)
(0.1)
2
·
1
2
(-0.0049)+
(3(0.1)
2
-1.2×0.1-0.07)
6×(0.1)
3
(0.0001)
=?-0.0532
3.4 In an examination, the number of students who obtained marks between
certain limits are given in the following table:
Using Newton's forward interpolation formula, find the number of students whose
marks be between 45 and 50 .
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