clear
clc
clf

intercepts

pause
hold off
x=0:0.1:3.*pi;
z1=sin(x);
z2=sin(2.*x);
z3=sin(3.*x);
y1=zeros(size(x));
y3=ones(size(x));
y2=y3./2;
plot3(x,y1,z1,'r',x,y2,z2,'b',x,y3,z3,'g')
grid on
xlabel('x-axis'), ylabel('y-axis'), zlabel('z-axis')

pause
theta=0:0.1:10.*pi;
plot3(sin(theta),cos(theta),theta)
grid on

pause
turns=40.*pi;
theta=linspace(0,turns,4000);
x=cos(theta).*(turns-theta)./turns;
y=sin(theta).*(turns-theta)./turns;
z=theta./turns;
plot3(x,y,z)
grid on
text(0.5,0.5,0.75,'Here is a piece of text!');

for in = 1:2
    pause
    N = 20;
    dvx = rand(1, N) - 0.5  % random v changes
    dvy = rand(1, N) - 0.5
    dvz = rand(1, N) - 0.5
    vx = cumsum(dvx);       % integrate to get v
    vy = cumsum(dvy);
    vz = cumsum(dvz);
    x = cumsum(vx);         % integrate to get pos
    y = cumsum(vy);
    z = cumsum(vz);
    plot3(x,y,z)
    grid on
    title('all 3 axes varying with parameter t')
    text(0,0,0,'start');
    text(x(N),y(N),z(N),'end');
end

pause
x=-3:3;
y=-3:3;
[xx,yy]=meshgrid(x,y)
zz=xx.^2 + yy.^2;
mesh(xx,yy,zz)

pause
hidden off

pause
[x,y,z]=peaks(30);
mesh(x,y,z)
axis tight
xlabel('x-axis'); ylabel('y-axis'); zlabel('z-axis')

pause
meshc(x,y,z)
axis tight

pause
meshz(x,y,z)
axis tight

pause
waterfall(x,y,z)
axis tight

pause
surf(x,y,z)
axis tight

pause
shading flat

pause
shading interp

pause
colorbar

pause
surf(x,y,z,y)
axis tight
shading interp

pause
C=del2(z); % compute Laplacian
surf(x,y,z,C)
axis tight
shading interp

pause
[xx,yy]=meshgrid(-4.*pi:pi./20:4.*pi);
R=sqrt(xx.^2 + yy.^2)+eps; % radius
zz=sin(R)./R;
surf(xx,yy,zz)
axis tight
shading interp

pause
lightangle(60, 45)

pause
facets = 120;  len = 2;  radius = 1;
thr = linspace(0, 2*pi, facets);
xr = linspace(0, len, facets);
[x, th] = meshgrid( xr, thr );
y = radius * cos(th);		 % Note 1
z = radius * sin(th);
surf(x, y, z);
shading interp
colormap bone			 % Note 2
axis equal,axis tight,axis off % Note 3
lightangle(60, 45) 		 % Note 4
alpha(0.8) 				 % Note 5
view(-20, 35)

pause
thr = linspace(0, 2*pi, facets); % range of theta
phir = linspace(0, pi, facets);  % range of phi
[th, phi] = meshgrid( thr, phir );
x = radius * cos(phi);
y = radius * sin(phi) .* cos(th);
z = radius * sin(phi) .* sin(th);
surf(x, y, z);
shading interp
colormap copper
axis equal, axis tight, axis off
lightangle(60, 45)

pause
colormap jet
kleinbottle
lightangle(60, 45)

pause
exploded = false
kestrel

pause
exploded = true
kestrel