% Once a plot has been displayed on the screen,
% hit the space bar to bring up the next plot

% The Elliptic Paraboloid z = 4x^2 + y^2

GraphZvsXY(-2,2,10,-2,2,10,'4*x.^2 + y.^2')
hold on
SpaceCurve(-2,2,10,'0','t','t.^2','b')
SpaceCurve(-2,2,10,'t','0','4*t.^2','r')

SpaceCurve(0,2*pi,100,'cos(t)','2*sin(t)','4','g') 
SpaceCurve(0,2*pi,100,'(2^0.5)*cos(t)','(2^0.5)*2*sin(t)','8','m')

view(-37,10)

pause

% The hyperbolic paraboloid z = y^2 - x^2

figure
GraphZvsXY(-1,1,10,-1,1,10,'y.^2-x.^2') 
hold on

SpaceCurve(-2^0.5,2^0.5,10,'t','-t','0','b')
SpaceCurve(-2^0.5,2^0.5,10,'t','t','0','r')

SpaceCurve(-2^0.5,2^0.5,10,'0.5*sinh(t)','0.5*cosh(t)','0.25','m')
SpaceCurve(-2^0.5,2^0.5,10,'0.5*cosh(t)','0.5*sinh(t)','-0.25','c')

%view(-60,20)
view(60,40)

% Intersection of two planes

pause

figure
ParametricSurface(-1,1,10,-1,1,10,'1+2*u+3*v','2+0.*u - 3*v','1-2*u-5*v' )
hold on
ParametricSurface(-1,1,10,-1,1,10,'1+4*u+1*v','2+2.*u - 1*v','1-3*u+4*v' )
view(38,14)