{VERSION 1 0 "X11/Motif" "1.0"}{GLOBALS 3 1}{FONT 0 "-adobe-helve tica-bold-r-normal--*-140-*-*-*-*-*-*" "helvetica" "Helvetica-Bol d" 8 14 0 "Helvetica-Bold" 14}{FONT 1 "-*-Times-medium-r-normal-- *-140-*-*-p-*-*-*" "Times" "Times-Roman" 4 14 64 "Times-Roman" 14 }{FONT 2 "-*-Courier-medium-r-normal--*-140-*-*-m-*-*-*" "Courier " "Courier" 4 14 192 "Courier" 14}{FONT 3 "-adobe-courier-bold-o- normal--*-180-*-*-*-*-*-*" "courier" "Courier-BoldOblique" 8 18 224 "Courier-BoldOblique" 18}{SCP_R 1 0 29{COM_R 2 0{TEXT 1 14 "b oymobedgan.ms"}}{COM_R 3 0{TEXT 1 123 "An animated sequence of p ictures which shows the edge of a disc tracing out a Boy's surfac e - model of a projective plane."}}{INP_R 4 0 "> "{TEXT 0 21 "res tart: 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+a 1*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 61 "plot3d([ a,b,c],u=0..2*Pi,v=(N-1)*Pi/(2*N)..(8*N-1)*Pi/(16*N),"}}{INP_R 22 0 "> "{TEXT 0 30 "grid=[4*gridsize,gridsize])]):"}}{INP_R 23 0 " > "{TEXT 0 35 "for p from 2 to 2*N-1 do View[p]:="}}{INP_R 24 0 "> "{TEXT 0 72 "display([textplot3d([1,-0.5,3,`getting it's edge \+ together to form....`],"}}{INP_R 25 0 "> "{TEXT 0 14 "colour=blac k),"}}{INP_R 26 0 "> "{TEXT 0 99 "plot3d([a,b,c],u=0..2*Pi,v=(2*N -1-p)*Pi/(4*N)..(2*N-p+1)*Pi/(4*N),grid=[4*gridsize,gridsize])]) \+ od:"}}{INP_R 27 0 "> "{TEXT 0 68 "display([seq(View[i],i=1..2*N-1 )],insequence=true,orientation=[0,0],"}}{INP_R 28 0 "> "{TEXT 0 58 "shading=NONE,ambientlight=[0,0.8,0],light=[90,-45,0,0,1]);"}} {SEP_R 29 0}{INP_R 30 0 "> "{TEXT 0 0 ""}}}{END}