% spline_fun.m
%
% This code originally used in MA 530 at NCSU.
%
%

% start with a clean slate
clear
clg
axis ([0 10 0 10])
hold on

% Initially, the list of points is empty
x = [ ];
y = [ ];
n = 0;

% Loop, picking up the points,
disp('Left mouse button picks points.')
disp('Right mouse button picks last point.')

but =1;
while but ==1
	[xi,yi,but] = ginput(1);
	plot(xi,yi,'go')
	n = n+1;
	x(n,1) = xi;
	y(n,1) = yi;
end

% Construct x_fine
for i=1:length(x)-1
  x_fine(:,i) = [x(i,1):(x(i+1,1)-x(i,1))/99:x(i+1,1)]';
end

% Construct the cubic spline
ys = spline(x, y, x_fine);

% Plot the interpolated curve
hp = plot(x', y', 'o',x_fine,ys);
xlabel('x');ylabel('u');
legend(hp,'Data Points','Cubic Spline');
title('Well Chosen Example of Data Points and Cubic Spline');
hold off