1. Save the following as integral.m
2. Change the path to your data2b input file
3. Then enter "integral" at matlab prompt (>>)to run it

function integral
load ../indat/data2b;		% load data
  [r,c]= size(data2b);		% size data matrix
  x=data2b(:,1);		% split data into x & y 
  y=data2b(:,2);
  points= 20;
  delta = (x(r)-x(1))/points;	%spacing of interpolated points
  xi=x(1):delta:x(r);		%interpolated data
  yi=interp1(x,y,xi,'spline');
plot(x,y,'ro',xi,yi,'b+');	%plot data
  grid;				%put on a grid
  axis([0 1 0 2.2]);		%fix axes length
  xlabel('x');			%label x-axis
ylabel('y');			%label y-axis
integral =trapz(xi,yi); 	%integrate
string =strcat('integral  = ',num2str(integral) );
				% put answer on plot
text(.5,1.0,string);
title('aero361 problem2b')	%put title on plot