function interpolation();

clear all;
clf reset
clc

global ComputeButton CleanButton ExitButton Exit;
global phandle ihandle x s p;

x = [0:0.0001:1]';
s = [];
p = [];

fig = gcf;
set(fig,'Unit','normal','Color',[1 1 1],...
    'Name','Interpolation','Number','off',...
    'MenuBar','none');
set(gca,'Position',[0 0 1.0 1.0],'Box','on',...
	'XLim',[0 1],'Ylim',[0 1],'Visible','off');
hold on
ihandle = plot(x,x*NaN,'b-');
phandle = plot(NaN,NaN,'r.', 'MarkerSize', 25);
drawnow

del = 0.1; posx = 0.05; posy = 0.85;
ComputeButton = uicontrol('style','push','string','compute', ...
     'units','normal','pos',[posx posy 2*del del], ...
     'call',['ComputeCallback' ]);
CleanButton = uicontrol('style','push','string','clean', ...
     'units','normal','pos',[posx+2*del posy 2*del del], ...
     'call',['CleanCallback' ]);
ExitButton = uicontrol('style','push','string','exit', ...
     'units','normal','pos',[posx+4*del posy 2*del del], ...
     'call',['ExitCallback' ]);
 
Exit = 0; 
xy = get(fig,'CurrentPoint');
while (Exit == 0 & ishandle(fig))
	xyprev = xy;
	xy = get(fig,'CurrentPoint');
	drawnow
	pause(0.2);
	if (xyprev ~= xy) 
		AddPoint(xy);
	end
end

% Ajout d'un point

function AddPoint(xy)
global ComputeButton CleanButton ExitButton Exit;
global phandle ihandle x s p;

snew = xy(1);
pnew = xy(2);
disp(['New data : ' num2str(snew) '    '  num2str(pnew) ]);
s = [s snew];
p = [p pnew];
set(ComputeButton,'back','default');
set(phandle,'Xdata',s,'Ydata',p);

% Calcul de l'interpolation

function ComputeCallback()
global ComputeButton CleanButton ExitButton Exit;
global phandle ihandle x s p;

n = length(s);
if (n >= 1)
	set(ihandle,'Ydata',polyval(polyfit(s,p,n-1),x));
	set(ComputeButton,'back',[.9 .6 .3]);
end

% Reset : suppression des données

function CleanCallback()
global ComputeButton CleanButton ExitButton Exit;
global phandle ihandle x s p;

s = [];
p = [];
set(ihandle,'Ydata',x*NaN);
set(phandle,'Xdata',NaN,'Ydata',NaN);
set(ComputeButton,'back','default');

% Exit : sortie du programme

function ExitCallback()
global ComputeButton CleanButton ExitButton stop gold;
global phandle ihandle x s p;

close;
Exit = 0;