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This resource provides an in-depth look into spline interpolation methods, a vital tool for engineering students. It covers the basics of interpolation, with a focus on polynomial and spline methods, demonstrating how to find values at unknown points based on given data. The document illustrates practical examples, including the application of linear and quadratic splines through a rocket velocity case study. Understanding these methods will enhance numerical problem-solving skills in engineering and contribute to STEM education.
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Spline Interpolation Method Major: All Engineering Majors Authors: Autar Kaw, Jai Paul http://numericalmethods.eng.usf.edu Transforming Numerical Methods Education for STEM Undergraduates http://numericalmethods.eng.usf.edu
Spline Method of Interpolationhttp://numericalmethods.eng.usf.edu
What is Interpolation ? Given (x0,y0), (x1,y1), …… (xn,yn), find the value of ‘y’ at a value of ‘x’ that is not given. http://numericalmethods.eng.usf.edu
Interpolants Polynomials are the most common choice of interpolants because they are easy to: • Evaluate • Differentiate, and • Integrate. http://numericalmethods.eng.usf.edu
Why Splines ? http://numericalmethods.eng.usf.edu
Why Splines ? Figure : Higher order polynomial interpolation is a bad idea http://numericalmethods.eng.usf.edu
Linear Interpolation http://numericalmethods.eng.usf.edu
Linear Interpolation (contd) http://numericalmethods.eng.usf.edu
Example The upward velocity of a rocket is given as a function of time in Table 1. Find the velocity at t=16 seconds using linear splines. Table Velocity as a function of time Figure. Velocity vs. time data for the rocket example http://numericalmethods.eng.usf.edu
Linear Interpolation http://numericalmethods.eng.usf.edu
Quadratic Interpolation http://numericalmethods.eng.usf.edu
Quadratic Interpolation (contd) http://numericalmethods.eng.usf.edu
Quadratic Splines (contd) http://numericalmethods.eng.usf.edu
Quadratic Splines (contd) http://numericalmethods.eng.usf.edu
Quadratic Splines (contd) http://numericalmethods.eng.usf.edu
Quadratic Spline Example The upward velocity of a rocket is given as a function of time. Using quadratic splines Find the velocity at t=16 seconds Find the acceleration at t=16 seconds Find the distance covered between t=11 and t=16 seconds Table Velocity as a function of time Figure. Velocity vs. time data for the rocket example http://numericalmethods.eng.usf.edu
Solution Let us set up the equations http://numericalmethods.eng.usf.edu
Each Spline Goes Through Two Consecutive Data Points http://numericalmethods.eng.usf.edu
Each Spline Goes Through Two Consecutive Data Points http://numericalmethods.eng.usf.edu
Derivatives are Continuous at Interior Data Points http://numericalmethods.eng.usf.edu
Derivatives are continuous at Interior Data Points At t=10 At t=15 At t=20 At t=22.5 http://numericalmethods.eng.usf.edu
Last Equation http://numericalmethods.eng.usf.edu
Final Set of Equations http://numericalmethods.eng.usf.edu
Coefficients of Spline http://numericalmethods.eng.usf.edu
Quadratic Spline InterpolationPart 2 of 2http://numericalmethods.eng.usf.edu http://numericalmethods.eng.usf.edu
Final Solution http://numericalmethods.eng.usf.edu
Velocity at a Particular Point a) Velocity at t=16 http://numericalmethods.eng.usf.edu
Acceleration from Velocity Profile b) The quadratic spline valid at t=16 is given by http://numericalmethods.eng.usf.edu
Distance from Velocity Profile c) Find the distance covered by the rocket from t=11s to t=16s. http://numericalmethods.eng.usf.edu
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 http://numericalmethods.eng.usf.edu/topics/spline_method.html
THE END http://numericalmethods.eng.usf.edu