/*Put the cursor on the line of code you want to execute. Hold down the shift key and press enter to 
execute the code. Code ends with either ";" or "$"*/

load(draw);

/*cylinder and ellipsoid plotted implicitly*/

draw3d(proportional_axes = xyz,
    color = "light-blue",
implicit(x^2/9 + y^2/16 = 1,
x,-5,5, y,-5,5, z,-3,3),
    color= red,line_width = 3,nticks = 40,
parametric(3*cos(t),4*sin(t),t/2,t,-2*%pi,2*%pi))$

draw3d(proportional_axes = xyz,
xyplane = 0,

x_voxel = 20,/*makes it plot more pts.  Default is 10*/
y_voxel = 20,
z_voxel = 20,
color = "light-blue",
implicit(x^2 + y^2 + z^2 = 1,x,-1.5,1.5,y,-1.5,1.5,z,-2.5,2.5),
color= black,line_width = 3,nticks = 40,
parametric(cos(t)*sin(sqrt(t)),sin(t)*sin(sqrt(t)),cos(sqrt(t)),t,0,2*%pi))$