Question

Develop, debug and test a program in Matlab to implement cubic spline interpolation. Calculate f(2.25) utilizing the data

x = 1.6, 2, 2.5, 3.2, 4, 4.5

f(x) = 2, 8, 14, 15, 8, 2

USE MATLAB CODE

Answer 1

Solution:

• My code uses in-built cubic spline interpolation code to compute output.
• csapi() takes input parameters x, f(x) and new values to compute, and fetch output for new values entered.

Matlab Code:

x = [1.6 2 2.5 3.2 4 4.5];
y = [2 8 14 15 8 2];
xx = 0:.25:5;
yy = csapi(x,y,xx);
plot(x,y,'o',xx,yy)

Output:

So output for f(2.25) is computed using:

• ans = csapi(x,y,2.25)
• This will give output: ans = 11.4167

PS: Let me know if you have any doubt.