Unit – 4
Numerical Integration
Q1) What is numerical integration?
A1)
Numerical integration is a process of evaluating or obtaining a definite integral from a set of numerical values of the integrand f(x).In case of function of single variable, the process is called quadrature.
Q2) What is Newton cotes formula?
A2)
Suppose where y takes the values
And let the integration interval (a,b) is divided into n equal sub-intervals, each of width h = b – a /n, so that,
x0 = a, x1 = x0 + h, x2 = x0 + 2h, . . . , xn = x0 + nh = b.
I =
The above formula is known as Newton’s cotes formula.
This is also known as general quadrature formula.
Q3) What is trapezoidal rule?
A3)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of.
Setting n=1, we get
Or I =
The above is known as Trapezoidal method.
Q4) State the trapezoidal rule for finding an approximate area under the given curve. A curve is given by the points (x, y) given below:
A4)
Estimate the area bounded by the curve, the x axis and the extreme ordinates.
We construct the data table:
X | 0 | 0.5 | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 | 3.5 | 4.0 |
Y | 23 | 19 | 14 | 11 | 12.5 | 16 | 19 | 20 | 20 |
Here length of interval h =0.5, initial value a = 0 and final value b = 4
By Trapezoidal method
Area of curve bounded on x axis =
Q5) Compute the value of ?
Using the trapezoidal rule with h=0.5, 0.25 and 0.125.
A5)
Here
For h=0.5, we construct the data table:
X | 0 | 0.5 | 1 |
Y | 1 | 0.8 | 0.5 |
By Trapezoidal rule
For h=0.25, we construct the data table:
X | 0 | 0.25 | 0.5 | 0.75 | 1 |
Y | 1 | 0.94117 | 0.8 | 0.64 | 0.5 |
By Trapezoidal rule
For h = 0.125, we construct the data table:
X | 0 | 0.125 | 0.25 | 0.375 | 0.5 | 0.625 | 0.75 | 0.875 | 1 |
Y | 1 | 0.98461 | 0.94117 | 0.87671 | 0.8 | 0.71910 | 0.64 | 0.56637 | 0.5 |
By Trapezoidal rule
[(1+0.5)+2(0.98461+0.94117+0.87671+0.8+0.71910+0.64+0.56637)]
Q6) Evaluate, using trapezoidal rule with five ordinates
A6)
Here
We construct the data table:
X | 0 | |||||
Y | 0 | 0.3693161 | 1.195328 | 1.7926992 | 1.477265 | 0 |
Q7) What is Simpson’s rule?
A7)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of.
Setting n = 2,
Which is known as Simpson’s 1/3- rule or Simpson’s rule.
Note: In this rule third and higher differences are neglected an so f(x) is a polynomial of degree 2.
Q8) Estimate the value of the integral
By Simpson’s rule with 4 strips and 8 strips respectively
A8)
For n=4, we have
Construct the data table:
X | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 |
Y=1/x | 1 | 0.66666 | 0.5 | 0.4 | 0.33333 |
By Simpson’s Rule
For n = 8, we have
X | 1 | 1.25 | 1.50 | 1.75 | 2.0 | 2.25 | 2.50 | 2.75 | 3.0 |
Y=1/x | 1 | 0.8 | 0.66666 | 0.571428 | 0.5 | 0.444444 | 0.4 | 0.3636363 | 0.333333 |
By Simpson’s Rule
Q9) Evaluate
A9)
Using Simpson’s 1/3 rule with .
For , we construct the data table:
X | 0 | ||||||
0 | 0.50874 | 0.707106 | 0.840896 | 0.930604 | 0.98281 | 1 |
By Simpson’s Rule
Q10) Using Simpson’s 1/3 rule with h = 1, evaluate
A10)
For h = 1, we construct the data table:
X | 3 | 4 | 5 | 6 | 7 |
9.88751 | 22.108709 | 40.23594 | 64.503340 | 95.34959 |
By Simpson’s Rule
= 177.3853
Q11) What is Simpson’s 3/8th rule?
A11)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of .
Setting n=3 , we get
Is known as Simpson’s 3/8 rule which is not as accurate as Simpson’s rule.
Q12) Evaluate
By Simpson’s 3/8 rule.
A12)
Let us divide the range of the interval [4, 5.2] into six equal parts.
For h=0.2, we construct the data table:
X | 4.0 | 4.2 | 4.4 | 4.6 | 4.8 | 5.0 | 5.2 |
1.3863 | 1.4351 | 1.4816 | 1.5261 | 1.5686 | 1.6094 | 1.6487 |
By Simpson’s 3/8 rule
= 1.8278475
Q13) Evaluate .
A13)
Let us divide the range of the interval [0,6] into six equal parts.
For h=1, we construct the data table:
X | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
1 | 0.5 | 0.2 | 0.1 | 0.0588 | 0.0385 | 0.027 |
By Simpson’s 3/8 rule
+3(0.0385)+0.027]
=1.3571
Q14) A river is 80 m wide. The depth ‘b’ of the river at a distance ‘a’ from one bank is given by the table-
a | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 |
B | 0 | 4 | 7 | 9 | 12 | 15 | 14 | 8 | 3 |
Find the approximate area of cross-section of the river using Boole’s rule.
A14)
The area of the cross-section of the river will be-
The number of sub-intervals here is 8.
Then by Boole’s rule-
= 2(10)/45 [ 7(0) + 32(4) + 12(7) + 32(9) + 7(12) + 7(12) + 32(15) + 12(14) + 32(8) +7(3)]
= 708
So that the area of of the cross-section of the river is 708 square meter.
Q15) Evaluate by using Boole’s.
A15)
Take h = , so that there four sub intervals-
X | 1 | 2 | 3 | 4 | 5 |
F(x) | 1 | ½ | 1/3 | ¼ | 1/5 |
Using Boole’s method-
Q16) Compute the following integral upto three decimal places by using Romberg’s method.
A16)
We take h = 0.5, 0.25 and 0.125 successively and use the results as below
I(h) = 0.7084, I(1/2h) = 0.6970 and I(1/4 h) = 0.6941
Hence,
We get
Finally,
The table of values,
0.7084
0.6932
0.6970 0.6931
0.6931
0.6941
Unit – 4
Numerical Integration
Q1) What is numerical integration?
A1)
Numerical integration is a process of evaluating or obtaining a definite integral from a set of numerical values of the integrand f(x).In case of function of single variable, the process is called quadrature.
Q2) What is Newton cotes formula?
A2)
Suppose where y takes the values
And let the integration interval (a,b) is divided into n equal sub-intervals, each of width h = b – a /n, so that,
x0 = a, x1 = x0 + h, x2 = x0 + 2h, . . . , xn = x0 + nh = b.
I =
The above formula is known as Newton’s cotes formula.
This is also known as general quadrature formula.
Q3) What is trapezoidal rule?
A3)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of.
Setting n=1, we get
Or I =
The above is known as Trapezoidal method.
Q4) State the trapezoidal rule for finding an approximate area under the given curve. A curve is given by the points (x, y) given below:
A4)
Estimate the area bounded by the curve, the x axis and the extreme ordinates.
We construct the data table:
X | 0 | 0.5 | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 | 3.5 | 4.0 |
Y | 23 | 19 | 14 | 11 | 12.5 | 16 | 19 | 20 | 20 |
Here length of interval h =0.5, initial value a = 0 and final value b = 4
By Trapezoidal method
Area of curve bounded on x axis =
Q5) Compute the value of ?
Using the trapezoidal rule with h=0.5, 0.25 and 0.125.
A5)
Here
For h=0.5, we construct the data table:
X | 0 | 0.5 | 1 |
Y | 1 | 0.8 | 0.5 |
By Trapezoidal rule
For h=0.25, we construct the data table:
X | 0 | 0.25 | 0.5 | 0.75 | 1 |
Y | 1 | 0.94117 | 0.8 | 0.64 | 0.5 |
By Trapezoidal rule
For h = 0.125, we construct the data table:
X | 0 | 0.125 | 0.25 | 0.375 | 0.5 | 0.625 | 0.75 | 0.875 | 1 |
Y | 1 | 0.98461 | 0.94117 | 0.87671 | 0.8 | 0.71910 | 0.64 | 0.56637 | 0.5 |
By Trapezoidal rule
[(1+0.5)+2(0.98461+0.94117+0.87671+0.8+0.71910+0.64+0.56637)]
Q6) Evaluate, using trapezoidal rule with five ordinates
A6)
Here
We construct the data table:
X | 0 | |||||
Y | 0 | 0.3693161 | 1.195328 | 1.7926992 | 1.477265 | 0 |
Q7) What is Simpson’s rule?
A7)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of.
Setting n = 2,
Which is known as Simpson’s 1/3- rule or Simpson’s rule.
Note: In this rule third and higher differences are neglected an so f(x) is a polynomial of degree 2.
Q8) Estimate the value of the integral
By Simpson’s rule with 4 strips and 8 strips respectively
A8)
For n=4, we have
Construct the data table:
X | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 |
Y=1/x | 1 | 0.66666 | 0.5 | 0.4 | 0.33333 |
By Simpson’s Rule
For n = 8, we have
X | 1 | 1.25 | 1.50 | 1.75 | 2.0 | 2.25 | 2.50 | 2.75 | 3.0 |
Y=1/x | 1 | 0.8 | 0.66666 | 0.571428 | 0.5 | 0.444444 | 0.4 | 0.3636363 | 0.333333 |
By Simpson’s Rule
Q9) Evaluate
A9)
Using Simpson’s 1/3 rule with .
For , we construct the data table:
X | 0 | ||||||
0 | 0.50874 | 0.707106 | 0.840896 | 0.930604 | 0.98281 | 1 |
By Simpson’s Rule
Q10) Using Simpson’s 1/3 rule with h = 1, evaluate
A10)
For h = 1, we construct the data table:
X | 3 | 4 | 5 | 6 | 7 |
9.88751 | 22.108709 | 40.23594 | 64.503340 | 95.34959 |
By Simpson’s Rule
= 177.3853
Q11) What is Simpson’s 3/8th rule?
A11)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of .
Setting n=3 , we get
Is known as Simpson’s 3/8 rule which is not as accurate as Simpson’s rule.
Q12) Evaluate
By Simpson’s 3/8 rule.
A12)
Let us divide the range of the interval [4, 5.2] into six equal parts.
For h=0.2, we construct the data table:
X | 4.0 | 4.2 | 4.4 | 4.6 | 4.8 | 5.0 | 5.2 |
1.3863 | 1.4351 | 1.4816 | 1.5261 | 1.5686 | 1.6094 | 1.6487 |
By Simpson’s 3/8 rule
= 1.8278475
Q13) Evaluate .
A13)
Let us divide the range of the interval [0,6] into six equal parts.
For h=1, we construct the data table:
X | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
1 | 0.5 | 0.2 | 0.1 | 0.0588 | 0.0385 | 0.027 |
By Simpson’s 3/8 rule
+3(0.0385)+0.027]
=1.3571
Q14) A river is 80 m wide. The depth ‘b’ of the river at a distance ‘a’ from one bank is given by the table-
a | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 |
B | 0 | 4 | 7 | 9 | 12 | 15 | 14 | 8 | 3 |
Find the approximate area of cross-section of the river using Boole’s rule.
A14)
The area of the cross-section of the river will be-
The number of sub-intervals here is 8.
Then by Boole’s rule-
= 2(10)/45 [ 7(0) + 32(4) + 12(7) + 32(9) + 7(12) + 7(12) + 32(15) + 12(14) + 32(8) +7(3)]
= 708
So that the area of of the cross-section of the river is 708 square meter.
Q15) Evaluate by using Boole’s.
A15)
Take h = , so that there four sub intervals-
X | 1 | 2 | 3 | 4 | 5 |
F(x) | 1 | ½ | 1/3 | ¼ | 1/5 |
Using Boole’s method-
Q16) Compute the following integral upto three decimal places by using Romberg’s method.
A16)
We take h = 0.5, 0.25 and 0.125 successively and use the results as below
I(h) = 0.7084, I(1/2h) = 0.6970 and I(1/4 h) = 0.6941
Hence,
We get
Finally,
The table of values,
0.7084
0.6932
0.6970 0.6931
0.6931
0.6941
Unit – 4
Numerical Integration
Q1) What is numerical integration?
A1)
Numerical integration is a process of evaluating or obtaining a definite integral from a set of numerical values of the integrand f(x).In case of function of single variable, the process is called quadrature.
Q2) What is Newton cotes formula?
A2)
Suppose where y takes the values
And let the integration interval (a,b) is divided into n equal sub-intervals, each of width h = b – a /n, so that,
x0 = a, x1 = x0 + h, x2 = x0 + 2h, . . . , xn = x0 + nh = b.
I =
The above formula is known as Newton’s cotes formula.
This is also known as general quadrature formula.
Q3) What is trapezoidal rule?
A3)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of.
Setting n=1, we get
Or I =
The above is known as Trapezoidal method.
Q4) State the trapezoidal rule for finding an approximate area under the given curve. A curve is given by the points (x, y) given below:
A4)
Estimate the area bounded by the curve, the x axis and the extreme ordinates.
We construct the data table:
X | 0 | 0.5 | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 | 3.5 | 4.0 |
Y | 23 | 19 | 14 | 11 | 12.5 | 16 | 19 | 20 | 20 |
Here length of interval h =0.5, initial value a = 0 and final value b = 4
By Trapezoidal method
Area of curve bounded on x axis =
Q5) Compute the value of ?
Using the trapezoidal rule with h=0.5, 0.25 and 0.125.
A5)
Here
For h=0.5, we construct the data table:
X | 0 | 0.5 | 1 |
Y | 1 | 0.8 | 0.5 |
By Trapezoidal rule
For h=0.25, we construct the data table:
X | 0 | 0.25 | 0.5 | 0.75 | 1 |
Y | 1 | 0.94117 | 0.8 | 0.64 | 0.5 |
By Trapezoidal rule
For h = 0.125, we construct the data table:
X | 0 | 0.125 | 0.25 | 0.375 | 0.5 | 0.625 | 0.75 | 0.875 | 1 |
Y | 1 | 0.98461 | 0.94117 | 0.87671 | 0.8 | 0.71910 | 0.64 | 0.56637 | 0.5 |
By Trapezoidal rule
[(1+0.5)+2(0.98461+0.94117+0.87671+0.8+0.71910+0.64+0.56637)]
Q6) Evaluate, using trapezoidal rule with five ordinates
A6)
Here
We construct the data table:
X | 0 | |||||
Y | 0 | 0.3693161 | 1.195328 | 1.7926992 | 1.477265 | 0 |
Q7) What is Simpson’s rule?
A7)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of.
Setting n = 2,
Which is known as Simpson’s 1/3- rule or Simpson’s rule.
Note: In this rule third and higher differences are neglected an so f(x) is a polynomial of degree 2.
Q8) Estimate the value of the integral
By Simpson’s rule with 4 strips and 8 strips respectively
A8)
For n=4, we have
Construct the data table:
X | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 |
Y=1/x | 1 | 0.66666 | 0.5 | 0.4 | 0.33333 |
By Simpson’s Rule
For n = 8, we have
X | 1 | 1.25 | 1.50 | 1.75 | 2.0 | 2.25 | 2.50 | 2.75 | 3.0 |
Y=1/x | 1 | 0.8 | 0.66666 | 0.571428 | 0.5 | 0.444444 | 0.4 | 0.3636363 | 0.333333 |
By Simpson’s Rule
Q9) Evaluate
A9)
Using Simpson’s 1/3 rule with .
For , we construct the data table:
X | 0 | ||||||
0 | 0.50874 | 0.707106 | 0.840896 | 0.930604 | 0.98281 | 1 |
By Simpson’s Rule
Q10) Using Simpson’s 1/3 rule with h = 1, evaluate
A10)
For h = 1, we construct the data table:
X | 3 | 4 | 5 | 6 | 7 |
9.88751 | 22.108709 | 40.23594 | 64.503340 | 95.34959 |
By Simpson’s Rule
= 177.3853
Q11) What is Simpson’s 3/8th rule?
A11)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of .
Setting n=3 , we get
Is known as Simpson’s 3/8 rule which is not as accurate as Simpson’s rule.
Q12) Evaluate
By Simpson’s 3/8 rule.
A12)
Let us divide the range of the interval [4, 5.2] into six equal parts.
For h=0.2, we construct the data table:
X | 4.0 | 4.2 | 4.4 | 4.6 | 4.8 | 5.0 | 5.2 |
1.3863 | 1.4351 | 1.4816 | 1.5261 | 1.5686 | 1.6094 | 1.6487 |
By Simpson’s 3/8 rule
= 1.8278475
Q13) Evaluate .
A13)
Let us divide the range of the interval [0,6] into six equal parts.
For h=1, we construct the data table:
X | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
1 | 0.5 | 0.2 | 0.1 | 0.0588 | 0.0385 | 0.027 |
By Simpson’s 3/8 rule
+3(0.0385)+0.027]
=1.3571
Q14) A river is 80 m wide. The depth ‘b’ of the river at a distance ‘a’ from one bank is given by the table-
a | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 |
B | 0 | 4 | 7 | 9 | 12 | 15 | 14 | 8 | 3 |
Find the approximate area of cross-section of the river using Boole’s rule.
A14)
The area of the cross-section of the river will be-
The number of sub-intervals here is 8.
Then by Boole’s rule-
= 2(10)/45 [ 7(0) + 32(4) + 12(7) + 32(9) + 7(12) + 7(12) + 32(15) + 12(14) + 32(8) +7(3)]
= 708
So that the area of of the cross-section of the river is 708 square meter.
Q15) Evaluate by using Boole’s.
A15)
Take h = , so that there four sub intervals-
X | 1 | 2 | 3 | 4 | 5 |
F(x) | 1 | ½ | 1/3 | ¼ | 1/5 |
Using Boole’s method-
Q16) Compute the following integral upto three decimal places by using Romberg’s method.
A16)
We take h = 0.5, 0.25 and 0.125 successively and use the results as below
I(h) = 0.7084, I(1/2h) = 0.6970 and I(1/4 h) = 0.6941
Hence,
We get
Finally,
The table of values,
0.7084
0.6932
0.6970 0.6931
0.6931
0.6941
Unit – 4
Unit – 4
Unit – 4
Numerical Integration
Q1) What is numerical integration?
A1)
Numerical integration is a process of evaluating or obtaining a definite integral from a set of numerical values of the integrand f(x).In case of function of single variable, the process is called quadrature.
Q2) What is Newton cotes formula?
A2)
Suppose where y takes the values
And let the integration interval (a,b) is divided into n equal sub-intervals, each of width h = b – a /n, so that,
x0 = a, x1 = x0 + h, x2 = x0 + 2h, . . . , xn = x0 + nh = b.
I =
The above formula is known as Newton’s cotes formula.
This is also known as general quadrature formula.
Q3) What is trapezoidal rule?
A3)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of.
Setting n=1, we get
Or I =
The above is known as Trapezoidal method.
Q4) State the trapezoidal rule for finding an approximate area under the given curve. A curve is given by the points (x, y) given below:
A4)
Estimate the area bounded by the curve, the x axis and the extreme ordinates.
We construct the data table:
X | 0 | 0.5 | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 | 3.5 | 4.0 |
Y | 23 | 19 | 14 | 11 | 12.5 | 16 | 19 | 20 | 20 |
Here length of interval h =0.5, initial value a = 0 and final value b = 4
By Trapezoidal method
Area of curve bounded on x axis =
Q5) Compute the value of ?
Using the trapezoidal rule with h=0.5, 0.25 and 0.125.
A5)
Here
For h=0.5, we construct the data table:
X | 0 | 0.5 | 1 |
Y | 1 | 0.8 | 0.5 |
By Trapezoidal rule
For h=0.25, we construct the data table:
X | 0 | 0.25 | 0.5 | 0.75 | 1 |
Y | 1 | 0.94117 | 0.8 | 0.64 | 0.5 |
By Trapezoidal rule
For h = 0.125, we construct the data table:
X | 0 | 0.125 | 0.25 | 0.375 | 0.5 | 0.625 | 0.75 | 0.875 | 1 |
Y | 1 | 0.98461 | 0.94117 | 0.87671 | 0.8 | 0.71910 | 0.64 | 0.56637 | 0.5 |
By Trapezoidal rule
[(1+0.5)+2(0.98461+0.94117+0.87671+0.8+0.71910+0.64+0.56637)]
Q6) Evaluate, using trapezoidal rule with five ordinates
A6)
Here
We construct the data table:
X | 0 | |||||
Y | 0 | 0.3693161 | 1.195328 | 1.7926992 | 1.477265 | 0 |
Q7) What is Simpson’s rule?
A7)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of.
Setting n = 2,
Which is known as Simpson’s 1/3- rule or Simpson’s rule.
Note: In this rule third and higher differences are neglected an so f(x) is a polynomial of degree 2.
Q8) Estimate the value of the integral
By Simpson’s rule with 4 strips and 8 strips respectively
A8)
For n=4, we have
Construct the data table:
X | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 |
Y=1/x | 1 | 0.66666 | 0.5 | 0.4 | 0.33333 |
By Simpson’s Rule
For n = 8, we have
X | 1 | 1.25 | 1.50 | 1.75 | 2.0 | 2.25 | 2.50 | 2.75 | 3.0 |
Y=1/x | 1 | 0.8 | 0.66666 | 0.571428 | 0.5 | 0.444444 | 0.4 | 0.3636363 | 0.333333 |
By Simpson’s Rule
Q9) Evaluate
A9)
Using Simpson’s 1/3 rule with .
For , we construct the data table:
X | 0 | ||||||
0 | 0.50874 | 0.707106 | 0.840896 | 0.930604 | 0.98281 | 1 |
By Simpson’s Rule
Q10) Using Simpson’s 1/3 rule with h = 1, evaluate
A10)
For h = 1, we construct the data table:
X | 3 | 4 | 5 | 6 | 7 |
9.88751 | 22.108709 | 40.23594 | 64.503340 | 95.34959 |
By Simpson’s Rule
= 177.3853
Q11) What is Simpson’s 3/8th rule?
A11)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of .
Setting n=3 , we get
Is known as Simpson’s 3/8 rule which is not as accurate as Simpson’s rule.
Q12) Evaluate
By Simpson’s 3/8 rule.
A12)
Let us divide the range of the interval [4, 5.2] into six equal parts.
For h=0.2, we construct the data table:
X | 4.0 | 4.2 | 4.4 | 4.6 | 4.8 | 5.0 | 5.2 |
1.3863 | 1.4351 | 1.4816 | 1.5261 | 1.5686 | 1.6094 | 1.6487 |
By Simpson’s 3/8 rule
= 1.8278475
Q13) Evaluate .
A13)
Let us divide the range of the interval [0,6] into six equal parts.
For h=1, we construct the data table:
X | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
1 | 0.5 | 0.2 | 0.1 | 0.0588 | 0.0385 | 0.027 |
By Simpson’s 3/8 rule
+3(0.0385)+0.027]
=1.3571
Q14) A river is 80 m wide. The depth ‘b’ of the river at a distance ‘a’ from one bank is given by the table-
a | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 |
B | 0 | 4 | 7 | 9 | 12 | 15 | 14 | 8 | 3 |
Find the approximate area of cross-section of the river using Boole’s rule.
A14)
The area of the cross-section of the river will be-
The number of sub-intervals here is 8.
Then by Boole’s rule-
= 2(10)/45 [ 7(0) + 32(4) + 12(7) + 32(9) + 7(12) + 7(12) + 32(15) + 12(14) + 32(8) +7(3)]
= 708
So that the area of of the cross-section of the river is 708 square meter.
Q15) Evaluate by using Boole’s.
A15)
Take h = , so that there four sub intervals-
X | 1 | 2 | 3 | 4 | 5 |
F(x) | 1 | ½ | 1/3 | ¼ | 1/5 |
Using Boole’s method-
Q16) Compute the following integral upto three decimal places by using Romberg’s method.
A16)
We take h = 0.5, 0.25 and 0.125 successively and use the results as below
I(h) = 0.7084, I(1/2h) = 0.6970 and I(1/4 h) = 0.6941
Hence,
We get
Finally,
The table of values,
0.7084
0.6932
0.6970 0.6931
0.6931
0.6941
Unit – 4
Unit – 4
Numerical Integration
Q1) What is numerical integration?
A1)
Numerical integration is a process of evaluating or obtaining a definite integral from a set of numerical values of the integrand f(x).In case of function of single variable, the process is called quadrature.
Q2) What is Newton cotes formula?
A2)
Suppose where y takes the values
And let the integration interval (a,b) is divided into n equal sub-intervals, each of width h = b – a /n, so that,
x0 = a, x1 = x0 + h, x2 = x0 + 2h, . . . , xn = x0 + nh = b.
I =
The above formula is known as Newton’s cotes formula.
This is also known as general quadrature formula.
Q3) What is trapezoidal rule?
A3)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of.
Setting n=1, we get
Or I =
The above is known as Trapezoidal method.
Q4) State the trapezoidal rule for finding an approximate area under the given curve. A curve is given by the points (x, y) given below:
A4)
Estimate the area bounded by the curve, the x axis and the extreme ordinates.
We construct the data table:
X | 0 | 0.5 | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 | 3.5 | 4.0 |
Y | 23 | 19 | 14 | 11 | 12.5 | 16 | 19 | 20 | 20 |
Here length of interval h =0.5, initial value a = 0 and final value b = 4
By Trapezoidal method
Area of curve bounded on x axis =
Q5) Compute the value of ?
Using the trapezoidal rule with h=0.5, 0.25 and 0.125.
A5)
Here
For h=0.5, we construct the data table:
X | 0 | 0.5 | 1 |
Y | 1 | 0.8 | 0.5 |
By Trapezoidal rule
For h=0.25, we construct the data table:
X | 0 | 0.25 | 0.5 | 0.75 | 1 |
Y | 1 | 0.94117 | 0.8 | 0.64 | 0.5 |
By Trapezoidal rule
For h = 0.125, we construct the data table:
X | 0 | 0.125 | 0.25 | 0.375 | 0.5 | 0.625 | 0.75 | 0.875 | 1 |
Y | 1 | 0.98461 | 0.94117 | 0.87671 | 0.8 | 0.71910 | 0.64 | 0.56637 | 0.5 |
By Trapezoidal rule
[(1+0.5)+2(0.98461+0.94117+0.87671+0.8+0.71910+0.64+0.56637)]
Q6) Evaluate, using trapezoidal rule with five ordinates
A6)
Here
We construct the data table:
X | 0 | |||||
Y | 0 | 0.3693161 | 1.195328 | 1.7926992 | 1.477265 | 0 |
Q7) What is Simpson’s rule?
A7)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of.
Setting n = 2,
Which is known as Simpson’s 1/3- rule or Simpson’s rule.
Note: In this rule third and higher differences are neglected an so f(x) is a polynomial of degree 2.
Q8) Estimate the value of the integral
By Simpson’s rule with 4 strips and 8 strips respectively
A8)
For n=4, we have
Construct the data table:
X | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 |
Y=1/x | 1 | 0.66666 | 0.5 | 0.4 | 0.33333 |
By Simpson’s Rule
For n = 8, we have
X | 1 | 1.25 | 1.50 | 1.75 | 2.0 | 2.25 | 2.50 | 2.75 | 3.0 |
Y=1/x | 1 | 0.8 | 0.66666 | 0.571428 | 0.5 | 0.444444 | 0.4 | 0.3636363 | 0.333333 |
By Simpson’s Rule
Q9) Evaluate
A9)
Using Simpson’s 1/3 rule with .
For , we construct the data table:
X | 0 | ||||||
0 | 0.50874 | 0.707106 | 0.840896 | 0.930604 | 0.98281 | 1 |
By Simpson’s Rule
Q10) Using Simpson’s 1/3 rule with h = 1, evaluate
A10)
For h = 1, we construct the data table:
X | 3 | 4 | 5 | 6 | 7 |
9.88751 | 22.108709 | 40.23594 | 64.503340 | 95.34959 |
By Simpson’s Rule
= 177.3853
Q11) What is Simpson’s 3/8th rule?
A11)
Let the interval be divided into n equal intervals such that <<….<=b.
Here.
To find the value of .
Setting n=3 , we get
Is known as Simpson’s 3/8 rule which is not as accurate as Simpson’s rule.
Q12) Evaluate
By Simpson’s 3/8 rule.
A12)
Let us divide the range of the interval [4, 5.2] into six equal parts.
For h=0.2, we construct the data table:
X | 4.0 | 4.2 | 4.4 | 4.6 | 4.8 | 5.0 | 5.2 |
1.3863 | 1.4351 | 1.4816 | 1.5261 | 1.5686 | 1.6094 | 1.6487 |
By Simpson’s 3/8 rule
= 1.8278475
Q13) Evaluate .
A13)
Let us divide the range of the interval [0,6] into six equal parts.
For h=1, we construct the data table:
X | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
1 | 0.5 | 0.2 | 0.1 | 0.0588 | 0.0385 | 0.027 |
By Simpson’s 3/8 rule
+3(0.0385)+0.027]
=1.3571
Q14) A river is 80 m wide. The depth ‘b’ of the river at a distance ‘a’ from one bank is given by the table-
a | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 |
B | 0 | 4 | 7 | 9 | 12 | 15 | 14 | 8 | 3 |
Find the approximate area of cross-section of the river using Boole’s rule.
A14)
The area of the cross-section of the river will be-
The number of sub-intervals here is 8.
Then by Boole’s rule-
= 2(10)/45 [ 7(0) + 32(4) + 12(7) + 32(9) + 7(12) + 7(12) + 32(15) + 12(14) + 32(8) +7(3)]
= 708
So that the area of of the cross-section of the river is 708 square meter.
Q15) Evaluate by using Boole’s.
A15)
Take h = , so that there four sub intervals-
X | 1 | 2 | 3 | 4 | 5 |
F(x) | 1 | ½ | 1/3 | ¼ | 1/5 |
Using Boole’s method-
Q16) Compute the following integral upto three decimal places by using Romberg’s method.
A16)
We take h = 0.5, 0.25 and 0.125 successively and use the results as below
I(h) = 0.7084, I(1/2h) = 0.6970 and I(1/4 h) = 0.6941
Hence,
We get
Finally,
The table of values,
0.7084
0.6932
0.6970 0.6931
0.6931
0.6941