> restart: with(plots):with(plottools):
> r:=6: a:=2: 
> x:=(r+a*cos(v))*cos(u):
> y:=(r+a*cos(v))*sin(u):
> z:=a*sin(v):
> torusz1:=plot3d([x,y,z],v=0..2*Pi,u=0..2*Pi,grid=[19,37]):
> t:=u/2:
> # Ha t:=0 vagy t:=Pi/2, azaz konstans, -> torusz2,torusz3:
> # Ha t:=u, 360 foknyival csavartuk  -> torusz4:
> x:=(r+a*cos(t)*sin(v)-sin(t)*sin(2*v))*cos(u):
> y:=(r+a*cos(t)*sin(v)-sin(t)*sin(2*v))*sin(u):
> z:=a*sin(t)*sin(v)+ cos(t)*sin(2*v):
> csavart:=plot3d([x,y,z],v=0..2*Pi,u=0..2*Pi,grid=[19,37]):
> vonal:=tubeplot([r*sin(u),r*cos(u),0],u=0..2*Pi,
>       radius=0.2,numpoints=37,tubepoints=5,
>         color=RED,style=PATCHNOGRID):
> d:=Pi/9:
> for i from 0 by 1 to 17 do    f[i]:=plot3d([x,y,z],v=0..2*Pi,u=i*d..(i+0.4)*d ,grid=[36,2]):
> od:
> L := [seq(f[i],i=0..17)]:
> display3d(csavart,vonal,orientation=[150,70],scaling=constrained);
> vrml(display3d(csavart,color=yellow,style=PATCHNOGRID,scaling=constrained,orientation=[147,73]),`csavartkk1.wrl`,background_color=COLOR(RGB,0,1,1), shininess=0.5, specular_color=COLOR(RGB,1,1,1)):


> display(csavart,vonal,scaling=constrained);
> display(L,vonal,scaling=constrained);
> display(torusz1,vonal,scaling=constrained);

> display(torusz2,vonal,scaling=constrained);

> display(torusz3,vonal,scaling=constrained);

> #display(torusz4,vonal,scaling=constrained);

> #display(torusz5,vonal,scaling=constrained);

>