% This m-file is an introduction to graphics and displaying text
clear
%% Displaying text
disp('This is an introduction to displaying text');
disp(' '); % Display a blank line
disp('Today is ...');
disp(date)
time=fix(clock); % Get time as integers
whos time % Structure of time matrix
hourstr=int2str(time(4)); % hours as a string (i.e. text)
minstr=int2str(time(5)); % hours as a string (i.e. text)
if time(5)<10
    minstr=['0',minstr]; % Add a leading zero if necessary
end
timex = [hourstr ':' minstr]; % create a time string
disp(' ');
disp('And the time is ...');
disp(timex);
%% Input and output
% Writing formatted data to a file (temperature conversion table)
F=-40:5:100;
C=(F-32)*5/9;
t=[F;C]; % creat a 2x100 matrix
fid=fopen('Temperature.table','w');
fprintf(fid,'   Temperature Table\n ');
fprintf(fid, 'Fahrenheit      Celsius \n');
fprintf(fid,'   %4i        %8.2f\n',t);
fclose(fid);
% Read formatted data, skipping header lines (text)
[temps(:,1),temps(:,2)] = textread('Temperature.table','%f%f','headerlines',2); 
disp(temps)
%% A line plot with several plots overlayed
t=linspace(0,2*pi,100); % Generate vector t
y1=sin(t); y2=t; y3=t-t.^3/6+t.^5/120;
plot(t,y1,t,y2,'--',t,y3,'o'); % Plot 3 curves
axis([0 5 -1 5]); % Set axes
xlabel('t');ylabel('Approximations of sin(t)');
title('First example graph');
legend('sin(t)','Linear approximation','3 terms of Taylor series');
% print -deps plot1.eps
% Can also overlay plots using hold and line commands
%% A contour plot
r=-5:0.2:5;
[X,Y]=meshgrid(r,r);
Z=-0.5*X.^2 + X.*Y + Y.^2;
cs=contour(X,Y,Z);
clabel(cs);
%% Surface plots
Z=cos(X).*cos(Y).*exp(-sqrt(X.^2+Y.^2)/4);
figure;surf(X,Y,Z);
figure;surfl(X,Y,Z);shading interp; colormap hot;
%% Animation
clf % clear other figures
theta=linspace(0,2*pi,100);x=cos(theta);y=sin(theta);
% Draw bead at initial position and assign a 'handle' (i.e. name)
hbead=line(x(1),y(1),'marker','o', 'markersize',8,'erase','background');
htrail=line(x(1),y(1),'marker','.', 'color','r','erase','none');
axis([-1.5 1.5 -1.5 1.5]);axis('square');xlabel('x');ylabel('y');
for k=2:length(theta) % Cycle through all positions
    set(hbead, 'xdata',x(k),'ydata',y(k));
    set(htrail,'xdata',x(k),'ydata',y(k));
    drawnow % Draw bead at new position
end