Quadratic Interpolation Formula: Function & Examples

Jasmine Grover logo

Jasmine Grover

Education Journalist | Study Abroad Strategy Lead

Interpolation is considered as the estimation of an unknown quantity or data point between two known quantities. Interpolation is simple if the seasonality, trends and long term cycles are available. The concept can be shown in regression analysis and series analysis in statistics. Though the interpolation algorithm is available as an in-built function in computers/ calculators, its formula has significance if the tabular form is available. Also represents an introduction for a bigger application of finite differences.

Read More: Probability and Statistics

Key Takeaways: Quadratic Interpolation, Function, Extrapolation, Lagrange Interpolation, Statistics, Algorithm, Quadratic interpolant


Quadratic Interpolation

[Click Here for Sample Questions]

Interpolation approaches are a common methods to the more general area of line search for 

Optimization. In quadratic interpolation, the critical value of a function is bracketed, and a quadratic interpolant is fitted to the arc contained in the interval. Following that, the interpolant is minimized, and a new interval is determined on the basis of relation of the minimizer to the actual endpoints of the interval. 

Quadratic Interpolation

Quadratic Interpolation

Interpolation is used to calculate the value of f(x) or a function of x from the known values of a function. If the values are known as x0 <....< xn and y0 = f(x0).....yn = f(xn) and x1 < x < xn, then the estimated values of f(x) are considered as interpolation. Similarly, if x > xn or x < x2 then the f(x) approximate value is known to be an extrapolation.

The video below explains this:

Quadratic Equations Detailed Video Explanation:

Read More:


Formula for Quadratic Interpolation

[Click Here for Sample Questions]

There are lagrange interpolation formulas and linear interpolation formulas that are used in order to identify the unknown values of a specific set of data points. The linear interpolation formula is known as follows:

Formula for Quadratic Interpolation

Formula for Quadratic Interpolation

In addition, Lagrange interpolation formula is as follows:

In addition, Lagrange interpolation formula is as follows:


Examples of Quadratic Interpolation

[Click Here for Sample Questions]

Interpolation helps to calculate the value of an unknown quantity between two known quantities. Similarly, polynomial interpolation is used to calculate the values between known data points. An example for interpolation is given as follows.

Consider a person who planted a tree and started measuring its height from day 1. He records the measure each day and on the fourth day decides to determine the height. The tabular data of the plant’s height is recorded below:

Days Height (mm)
1 0
3 4
5 8
7 12
9 16
11 20

Using the given data, one can determine the height of the plant on any random day. The height on day four is estimated as 6 mm. Also, with the data we can say that the plant grows in a linear pattern. The pattern shows a straight line and the height can be determined by plotting the data on a graph. In case the plant stops growing in a linear direction, then the pattern takes the form of a curve. Linear interpolation formula is an effective way to solve this mathematical problem.


Things to Remember

  • Interpolation is considered as the estimation of an unknown data point between two known quantities.
  • Interpolation concept can be expressed in regression analysis and series analysis in statistics.
  • The formula is used to determine the unknown values for any data related to geography such as elevation, rainfall, noise level, etc.
  • There are various types of interpolation methods such as biharmonic interpolation method, thin-plate spline method, cubic spline method, linear interpolation, etc.

Also Read:


Sample Questions

Ques: Explain Lagrange interpolation formula? (2 marks)

Ans: Lagrange interpolation formula can be used to determine a polynomial known as Lagrange polynomial, which takes on specific values at arbitrary points. It is an nth degree polynomial approximation to f(x).

Ques: What is an interpolation? (2 marks)

Ans: Interpolation helps in calculating an unknown value that comes between known values. Suppose, a straight passes through two known points. Using the known values, we can estimate the point of the unknown value.

Ques: What are some advantages and disadvantages of Lagrange interpolation? (2 marks)

Ans: It is simple and easy to remember. The application of the formula is not swift. The disadvantage is that the chances of getting errors is high. Also, one cannot determine if the functional values used for the calculation are correct or not. 

Ques: Define linear interpolation? (2 marks)

Ans: Linear interpolation is used to calculate values at a point in between a given point. The points are conjoined by a simple line segment. Each segment can be interpolated individually. The values on the interrelated line can be estimated via the parameter mu. Linear interpolation is used to calculate the values of internet rate for a point or security in which no data is provided.

Ques: How to identify the interpolation between two numbers? (2 marks)

Ans: Consider the formula y = y1 + ((x – x1) / (x2 – x1)) * (y2 – y1). The known value is x and y is the unknown value. The coordinates below the known value x are x1 and y1. The coordinates above the x value are x2 and y2.

Ques: What produces smooth interpolation? (2 marks)

Ans: The smoother interpolants are being produced by polynomial interpolation and spline interpolation.

For Latest Updates on Upcoming Board Exams, Click Here: https://t.me/class_10_12_board_updates


Check-Out: 

CBSE CLASS XII Related Questions

  • 1.

    A racing track is built around an elliptical ground whose equation is given by \[ 9x^2 + 16y^2 = 144 \] The width of the track is \(3\) m as shown. Based on the given information answer the following: 

    (i) Express \(y\) as a function of \(x\) from the given equation of ellipse. 
    (ii) Integrate the function obtained in (i) with respect to \(x\). 
    (iii)(a) Find the area of the region enclosed within the elliptical ground excluding the track using integration. 
    OR 
    (iii)(b) Write the coordinates of the points \(P\) and \(Q\) where the outer edge of the track cuts \(x\)-axis and \(y\)-axis in first quadrant and find the area of triangle formed by points \(P,O,Q\). 
     


      • 2.

        Smoking increases the risk of lung problems. A study revealed that 170 in 1000 males who smoke develop lung complications, while 120 out of 1000 females who smoke develop lung related problems. In a colony, 50 people were found to be smokers of which 30 are males. A person is selected at random from these 50 people and tested for lung related problems. Based on the given information answer the following questions: 

        (i) What is the probability that selected person is a female? 
        (ii) If a male person is selected, what is the probability that he will not be suffering from lung problems? 
        (iii)(a) A person selected at random is detected with lung complications. Find the probability that selected person is a female. 
        OR 
        (iii)(b) A person selected at random is not having lung problems. Find the probability that the person is a male. 
         


          • 3.

            A rectangle of perimeter \(24\) cm is revolved along one of its sides to sweep out a cylinder of maximum volume. Find the dimensions of the rectangle. 


              • 4.
                Obtain the value of \[ \Delta = \begin{vmatrix} 1 + x & 1 & 1 \\ 1 & 1 + y & 1 \\ 1 & 1 & 1 + z \end{vmatrix} \] in terms of \(x, y, z\). Further, if \(\Delta = 0\) and \(x, y, z\) are non–zero real numbers, prove that \[ x^{-1} + y^{-1} + z^{-1} = -1 \]


                  • 5.
                    A line passing through the points \(A(1,2,3)\) and \(B(6,8,11)\) intersects the line \[ \vec r = 4\hat i + \hat j + \lambda(6\hat i + 2\hat j + \hat k) \] Find the coordinates of the point of intersection. Hence write the equation of a line passing through the point of intersection and perpendicular to both the lines.


                      • 6.
                        Find : \[ \int \frac{2x+1}{\sqrt{x^2+6x}}\,dx \]

                          CBSE CLASS XII Previous Year Papers

                          Comments


                          No Comments To Show