1. Newton’s Divided Difference Polynomial Method of Interpolation
Industrial Engineering Majors
Authors: Autar Kaw, Jai Paul
Transforming Numerical Methods Education for STEM Undergraduates

2. Newton’s Divided Difference Method of Interpolation http://numericalmethods.eng.usf.edu

3. What is Interpolation ?
Given (x0,y0), (x1,y1), …… (xn,yn), find the value of ‘y’ at a value of ‘x’ that is not given.

4. Interpolants Evaluate Differentiate, and Integrate.
Polynomials are the most common choice of interpolants because they are easy to:
Evaluate
Differentiate, and
Integrate.

5. Newton’s Divided Difference Method
Linear interpolation: Given pass a linear interpolant through the data
where

6. Example
A curve needs to be fit through the given points to fabricate the cam. If the cam follows a straight line profile between x = 1.28 to x = 0.66, what is the value of y at x=1.1 ? Find using the Newton’s divided difference method for linear interpolation.
Point
x (in.)
y (in.) 1
2.20
0.00 2
1.28
0.88 3
0.66
1.14 4
1.20 5
–0.60
1.04 6
–1.04
0.60 7
–1.20 1 2 3 5 6 7 X Y 4

7. Linear Interpolation

8. Linear Interpolation (contd)

9. Quadratic Interpolation

10. Example
A curve needs to be fit through the given points to fabricate the cam. If the cam follows a straight line profile between x = 1.28 to x = 0.66, what is the value of y at x=1.1 ? Find using the Newton’s divided difference method for quadratic interpolation.
Point
x (in.)
y (in.) 1
2.20
0.00 2
1.28
0.88 3
0.66
1.14 4
1.20 5
–0.60
1.04 6
–1.04
0.60 7
–1.20 1 2 3 5 6 7 X Y 4

11. Quadratic Interpolation (contd)

12. Quadratic Interpolation (contd)

13. Quadratic Interpolation (contd)

14. General Form
where
Rewriting

15. General Form

16. General form

17. Example
A curve needs to be fit through the given points to fabricate the cam. If the cam follows a straight line profile between x = 1.28 to x = 0.66, what is the value of y at x=1.1 ? Find using the Newton’s divided difference method for a sixth order polynomial.
Point
x (in.)
y (in.) 1
2.20
0.00 2
1.28
0.88 3
0.66
1.14 4
1.20 5
–0.60
1.04 6
–1.04
0.60 7
–1.20 1 2 3 5 6 7 X Y 4

18. Example

19. Example

20. Example

21. Example

22. Additional Resources
For all resources on this topic such as digital audiovisual lectures, primers, textbook chapters, multiple-choice tests, worksheets in MATLAB, MATHEMATICA, MathCad and MAPLE, blogs, related physical problems, please visit

23. THE END