cat.m

把Arnold cat映射进行修改

function [lastimage]=cat(a,b,image,n2)
n=length(image); 
c=a*b+1;
for q=1:n2
 for i=0:n-1                       %%%%%%%%%%%  置换一次  
           for j=0:n-1
           x=mod(i+a*j,n); 
           y=mod(b*i+c*j,n); 
           lastimage(x+1,y+1)=image(i+1,j+1);
                      end
 end
 image=lastimage;
end