Need command of this MATLAB question

Question

x 1.6 2 2.5 3.2 4 4.5

f(x) 2 8 14 15 8 2

Calculate f(2.8) using Newton’s interpolating polynomials (function interp1) in MATLAB

f(2.8) =

Answer 1

%% define known data points

x = [1.6 2 2.5 3.2 4 4.5]; %x

fx = [2 8 14 15 8 2]; %f(x)

%% use interp1 function to estimate unknown data point

help interp1 %read help to learn about how interp1 function works and what arguments it expects

q =2.8; %point to evaluate

fq = interp1(x,fx,q); %interpolated estimate of f(q)

%% display results

disp(['f(',num2str(q),') = ',num2str(fq)]); %display answer to user

figure; plot(x,fx,'ko--'); hold on; plot(q,fq,'r*'); %plot results to check validity

xlabel('x'); ylabel('f(x)'); %add labels