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0 ""}}{COM_R 3 0{TEXT 1 140 "An animated  sequence of pictures wh
ich shows a Mobius band getting its edge together to make a Boy's
 surface - model of a projective plane."}}{INP_R 4 0 "> "{TEXT 0 
21 "restart: with(plots):"}}{INP_R 5 0 "> "{TEXT 0 18 "r:=-cos(u)
*sin(v):"}}{INP_R 6 0 "> "{TEXT 0 17 "s:=sin(u)*sin(v):"}}{INP_R 
7 0 "> "{TEXT 0 10 "t:=cos(v):"}}{INP_R 8 0 "> "{TEXT 0 48 "a1:=(
1/3)^(1/2):b1:=(1/6)^(1/2):c1:=(1/2)^(1/2):"}}{INP_R 9 0 "> "
{TEXT 0 18 "x:=c1*r+b1*s+a1*t:"}}{INP_R 10 0 "> "{TEXT 0 19 "y:=-
c1*r+b1*s+a1*t:"}}{INP_R 11 0 "> "{TEXT 0 18 "z:=-(2*b1)*s+a1*t:"
}}{INP_R 12 0 "> "{TEXT 0 9 "d:=x+y+z:"}}{INP_R 13 0 "> "{TEXT 0 
17 "g:=(x^2+y^2+z^2):"}}{INP_R 14 0 "> "{TEXT 0 69 "a:=((2*x^2-y^
2-z^2)*g+2*y*z*(y^2-z^2)+z*x*(x^2-z^2)+x*y*(y^2-x^2))/2:"}}{INP_R
 15 0 "> "{TEXT 0 57 "b:=((y^2-z^2)*g+z*x*(z^2-x^2)+x*y*(y^2-x^2)
)*(sqrt(3))/2:"}}{INP_R 16 0 "> "{TEXT 0 33 "c:=d*((d^3)/4+(y-x)*
(z-y)*(x-z)):"}}{INP_R 17 0 "> "{TEXT 0 19 "gridsize:=10:N:=12:"}
}{INP_R 18 0 "> "{TEXT 0 9 "View[1]:="}}{INP_R 19 0 "> "{TEXT 0 
51 "display([textplot3d([1,-0.5,3,`A Mobius band....`],"}}{INP_R 
20 0 "> "{TEXT 0 14 "colour=black),"}}{INP_R 21 0 "> "{TEXT 0 48 
"plot3d([a,b,c],u=0..2*Pi,v=(N-1)*Pi/(2*N)..Pi/2,"}}{INP_R 22 0 "
> "{TEXT 0 30 "grid=[4*gridsize,gridsize])]):"}}{INP_R 23 0 "> "
{TEXT 0 33 "for p from 2  to N-1 do View[p]:="}}{INP_R 24 0 "> "
{TEXT 0 72 "display([textplot3d([1,-0.5,3,`getting it's edge toge
ther to form....`],"}}{INP_R 25 0 "> "{TEXT 0 14 "colour=black),"
}}{INP_R 26 0 "> "{TEXT 0 81 "plot3d([a,b,c],u=0..2*Pi,v=(N-p)*Pi
/(2*N)..Pi/2,grid=[4*gridsize,gridsize])]) od:"}}{OUT_R 27 0 26
{TEXT 2 1 "\012"}}{INP_R 28 0 "> "{TEXT 0 9 "View[N]:="}}{INP_R 
29 0 "> "{TEXT 0 49 "display([textplot3d([1,-0.5,3,`a Boy's surfa
ce`],"}}{INP_R 30 0 "> "{TEXT 0 14 "colour=black),"}}{INP_R 31 0 
"> "{TEXT 0 65 "plot3d([a,b,c],u=0..2*Pi,v=0..Pi/2,grid=[4*gridsi
ze,gridsize])]):"}}{INP_R 32 0 "> "{TEXT 0 64 "display([seq(View[
i],i=1..N)],insequence=true,orientation=[0,0],"}}{INP_R 33 0 "> "
{TEXT 0 58 "shading=NONE,ambientlight=[0,0.8,0],light=[90,-45,0,0
,1]);"}}}{END}