testattractor3.m

%2D Quadratic attractor
%
%author:Ankur Pawar
%description:generating strange attractor using histogram method.
%execution time about 25 seconds
%Equation
%xn+1 = a0 + a1 xn + a2 xn^2 + a3 xn yn + a4 yn + a5 yn^2 
%yn+1 = b0 + b1 xn + b2 xn^2 + b3 xn yn + b4 yn + b5 yn^2
%attractorcoeff.mat contains list of coefficients

xres=1000;
yres=1000;
load attractorcoeff
liststr={'1';'2';'3';'4';'6';'7';
         '9';'11';'12';'13';'14';
         '15';'16';'17';'18';'19';
         '21';'23'};
[ss,v] = listdlg('PromptString','Select any one ',...
                'SelectionMode','single',...
                'ListString',liststr);
if v==1
    ss = str2num(liststr{ss});
    co = coeff(ss,:);
    xn = 0; yn = 0; xi = 0; yi = 0; xxn = 0;
    xmin=0;xmax=0;ymin=0;ymax=0;
    h_msg =  msgbox(' Please Wait ',' ');
    for n=1:5000               %loop to find min and max value of x and y
      xxn=co(1)+co(2)*xn+co(3)*xn^2+co(4)*xn*yn+...
         co(5)*yn+co(6)*yn^2; 
      yn=co(7)+co(8)*xn+co(9)*xn^2+co(10)*xn*yn+...
         co(11)*yn+co(12)*yn^2; 
      xn=xxn;
      xmin=min(xmin,xn);
      xmax=max(xmax,xn);
      ymin=min(ymin,yn);
      ymax=max(ymax,yn);
      xi=xn;
      yi=yn;
   end

    z=zeros(xres,yres,3);     %3D histogram array
    xdiff=1.05*((xmax)-(xmin))/xres;
    ydiff=1.05*((ymax)-(ymin))/yres;
    minx=1.05*xmin;
    miny=1.05*ymin;
   

    xn=0;yn=0;xi=0;yi=0;xxn=0;
    total=20;
    for m=1:total
       
       for n=1:1300000
           
           xxn=co(1)+co(2)*xn+co(3)*xn^2+co(4)*xn*yn+...
               co(5)*yn+co(6)*yn^2; 
            yn=co(7)+co(8)*xn+co(9)*xn^2+co(10)*xn*yn+...
               co(11)*yn+co(12)*yn^2; 
            xn=xxn;
            xi=xn;
            yi=yn;
            a=mod(xn,1);
           s=1;
           v=1;
           zo = floor(6*a); 
           rough = (zo); 
           f = a*6 - zo;
           p = v*(1-s);
           q = v*(1-s*f);
           t = v*(1-s*(1-f));
 
           switch (rough)    
          case 0 
                r=v; g=t; b=p;
          case 1 
                r=q; g=v; b=p;
          case 2 
                r=p; g=v; b=t;
          case 3 
                r=p; g=q; b=v;
          case 4 
                r=t; g=p; b=v;
          case 5 
                r=v; g=p; b=q;
          end             
          
          indx=floor((xi-minx)/xdiff);
          indy=floor((yi-miny)/ydiff);
          z(indx,indy,1)=z(indx,indy,1)+r;
          z(indx,indy,2)=z(indx,indy,2)+g;
          z(indx,indy,3)=z(indx,indy,3)+b;
       end
    end
close(h_msg);
h=0.5*fspecial('average',[2 2]);
z=imfilter(z,h);
imwrite(uint8(256-z),['3attr' num2str(ss) '.png'],'png');
image(uint8(256-z))
end