Plotting a subset of the 4-sphere in the stereographic projection












3












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I'm looking for a program, library or function in a math language (SAGE will be fantastic) that allows me to plot in 3D a subset of $mathbb{S}^4$ through the canonical stereographic projection that sends it, minus a point, in $mathbb{R}^3$.



Someone know something that allows me to do it? Thank you in advance.



PS: Sorry for my English, it is not my mother language.










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    3












    $begingroup$


    I'm looking for a program, library or function in a math language (SAGE will be fantastic) that allows me to plot in 3D a subset of $mathbb{S}^4$ through the canonical stereographic projection that sends it, minus a point, in $mathbb{R}^3$.



    Someone know something that allows me to do it? Thank you in advance.



    PS: Sorry for my English, it is not my mother language.










    share|cite|improve this question









    $endgroup$















      3












      3








      3





      $begingroup$


      I'm looking for a program, library or function in a math language (SAGE will be fantastic) that allows me to plot in 3D a subset of $mathbb{S}^4$ through the canonical stereographic projection that sends it, minus a point, in $mathbb{R}^3$.



      Someone know something that allows me to do it? Thank you in advance.



      PS: Sorry for my English, it is not my mother language.










      share|cite|improve this question









      $endgroup$




      I'm looking for a program, library or function in a math language (SAGE will be fantastic) that allows me to plot in 3D a subset of $mathbb{S}^4$ through the canonical stereographic projection that sends it, minus a point, in $mathbb{R}^3$.



      Someone know something that allows me to do it? Thank you in advance.



      PS: Sorry for my English, it is not my mother language.







      math-software stereographic-projections






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      share|cite|improve this question











      share|cite|improve this question




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      asked May 27 '18 at 12:39









      Davide F.Davide F.

      418213




      418213






















          1 Answer
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          $begingroup$

          Is your question connected to the so-called Hopf fibration as illustrated on the following figure ?



          enter image description here



          Fig. 1 : Foliation of the 4-sphere by an infinite set of torii, a few of them being represented by their family of Villarceau circles.



          I have obtained this figure with the following Matlab program where the essential instruction is "u=a*v". I can provide more details ; you can find some in the following document : %http://mathhelpforum.com/differential-geometry/109193-hopf-fibration.html



          clear all;close all;hold on;axis equal off;
          set(gcf,'color','w');i=complex(0,1);
          axis([-2,2,-2,2,-2,2]);
          t=0:0.01:2*pi;
          nc=30; % number of circles on each torus
          nt=3; % number of torii
          d=0.; % if d = 0 : torii ; if d > 0 : cyclides
          cc=[0. 0.6 0.4
          1 0. 0.5
          0 0 0.]; % table of colors (must have nt rows)
          for L=1:nt;
          c=cc(L,:);
          for K=1:nc;
          a=d+L*exp(i*2*pi*K/nc);
          R=1/sqrt(1+abs(a)^2);v=R*exp(i*t);
          u=a*v;
          ux=real(u);uy=imag(u);
          vx=real(v);vy=imag(v);
          D=1-vy;
          x=ux./D;y=uy./D;z=vx./D; % stereographic projection
          plot3(x,y,z,'color',c,'linewidth',1);
          end;
          end;
          view([-44,6]);





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            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            0












            $begingroup$

            Is your question connected to the so-called Hopf fibration as illustrated on the following figure ?



            enter image description here



            Fig. 1 : Foliation of the 4-sphere by an infinite set of torii, a few of them being represented by their family of Villarceau circles.



            I have obtained this figure with the following Matlab program where the essential instruction is "u=a*v". I can provide more details ; you can find some in the following document : %http://mathhelpforum.com/differential-geometry/109193-hopf-fibration.html



            clear all;close all;hold on;axis equal off;
            set(gcf,'color','w');i=complex(0,1);
            axis([-2,2,-2,2,-2,2]);
            t=0:0.01:2*pi;
            nc=30; % number of circles on each torus
            nt=3; % number of torii
            d=0.; % if d = 0 : torii ; if d > 0 : cyclides
            cc=[0. 0.6 0.4
            1 0. 0.5
            0 0 0.]; % table of colors (must have nt rows)
            for L=1:nt;
            c=cc(L,:);
            for K=1:nc;
            a=d+L*exp(i*2*pi*K/nc);
            R=1/sqrt(1+abs(a)^2);v=R*exp(i*t);
            u=a*v;
            ux=real(u);uy=imag(u);
            vx=real(v);vy=imag(v);
            D=1-vy;
            x=ux./D;y=uy./D;z=vx./D; % stereographic projection
            plot3(x,y,z,'color',c,'linewidth',1);
            end;
            end;
            view([-44,6]);





            share|cite|improve this answer











            $endgroup$


















              0












              $begingroup$

              Is your question connected to the so-called Hopf fibration as illustrated on the following figure ?



              enter image description here



              Fig. 1 : Foliation of the 4-sphere by an infinite set of torii, a few of them being represented by their family of Villarceau circles.



              I have obtained this figure with the following Matlab program where the essential instruction is "u=a*v". I can provide more details ; you can find some in the following document : %http://mathhelpforum.com/differential-geometry/109193-hopf-fibration.html



              clear all;close all;hold on;axis equal off;
              set(gcf,'color','w');i=complex(0,1);
              axis([-2,2,-2,2,-2,2]);
              t=0:0.01:2*pi;
              nc=30; % number of circles on each torus
              nt=3; % number of torii
              d=0.; % if d = 0 : torii ; if d > 0 : cyclides
              cc=[0. 0.6 0.4
              1 0. 0.5
              0 0 0.]; % table of colors (must have nt rows)
              for L=1:nt;
              c=cc(L,:);
              for K=1:nc;
              a=d+L*exp(i*2*pi*K/nc);
              R=1/sqrt(1+abs(a)^2);v=R*exp(i*t);
              u=a*v;
              ux=real(u);uy=imag(u);
              vx=real(v);vy=imag(v);
              D=1-vy;
              x=ux./D;y=uy./D;z=vx./D; % stereographic projection
              plot3(x,y,z,'color',c,'linewidth',1);
              end;
              end;
              view([-44,6]);





              share|cite|improve this answer











              $endgroup$
















                0












                0








                0





                $begingroup$

                Is your question connected to the so-called Hopf fibration as illustrated on the following figure ?



                enter image description here



                Fig. 1 : Foliation of the 4-sphere by an infinite set of torii, a few of them being represented by their family of Villarceau circles.



                I have obtained this figure with the following Matlab program where the essential instruction is "u=a*v". I can provide more details ; you can find some in the following document : %http://mathhelpforum.com/differential-geometry/109193-hopf-fibration.html



                clear all;close all;hold on;axis equal off;
                set(gcf,'color','w');i=complex(0,1);
                axis([-2,2,-2,2,-2,2]);
                t=0:0.01:2*pi;
                nc=30; % number of circles on each torus
                nt=3; % number of torii
                d=0.; % if d = 0 : torii ; if d > 0 : cyclides
                cc=[0. 0.6 0.4
                1 0. 0.5
                0 0 0.]; % table of colors (must have nt rows)
                for L=1:nt;
                c=cc(L,:);
                for K=1:nc;
                a=d+L*exp(i*2*pi*K/nc);
                R=1/sqrt(1+abs(a)^2);v=R*exp(i*t);
                u=a*v;
                ux=real(u);uy=imag(u);
                vx=real(v);vy=imag(v);
                D=1-vy;
                x=ux./D;y=uy./D;z=vx./D; % stereographic projection
                plot3(x,y,z,'color',c,'linewidth',1);
                end;
                end;
                view([-44,6]);





                share|cite|improve this answer











                $endgroup$



                Is your question connected to the so-called Hopf fibration as illustrated on the following figure ?



                enter image description here



                Fig. 1 : Foliation of the 4-sphere by an infinite set of torii, a few of them being represented by their family of Villarceau circles.



                I have obtained this figure with the following Matlab program where the essential instruction is "u=a*v". I can provide more details ; you can find some in the following document : %http://mathhelpforum.com/differential-geometry/109193-hopf-fibration.html



                clear all;close all;hold on;axis equal off;
                set(gcf,'color','w');i=complex(0,1);
                axis([-2,2,-2,2,-2,2]);
                t=0:0.01:2*pi;
                nc=30; % number of circles on each torus
                nt=3; % number of torii
                d=0.; % if d = 0 : torii ; if d > 0 : cyclides
                cc=[0. 0.6 0.4
                1 0. 0.5
                0 0 0.]; % table of colors (must have nt rows)
                for L=1:nt;
                c=cc(L,:);
                for K=1:nc;
                a=d+L*exp(i*2*pi*K/nc);
                R=1/sqrt(1+abs(a)^2);v=R*exp(i*t);
                u=a*v;
                ux=real(u);uy=imag(u);
                vx=real(v);vy=imag(v);
                D=1-vy;
                x=ux./D;y=uy./D;z=vx./D; % stereographic projection
                plot3(x,y,z,'color',c,'linewidth',1);
                end;
                end;
                view([-44,6]);






                share|cite|improve this answer














                share|cite|improve this answer



                share|cite|improve this answer








                edited Dec 15 '18 at 22:54

























                answered Dec 11 '18 at 17:03









                Jean MarieJean Marie

                29.7k42051




                29.7k42051






























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