Matlab code for histogram equalization

a= imread('test.jpg');
c=rgb2gray(a);
b= size(c);
t=b(1);
s=b(2);
tem=uint8(zeros(t,s));
re=zeros(1,256);
  
    for n=1:t
        for m=1:s          
                re(c(n,m)+1)=re(c(n,m)+1)+1          
        end
    end
    tmp=re;
x=re/(t*s);
y=x*255;
%%%%%%%%%%%%%%%%%%%%%
cu(1)=y(1);
for s1=2:256
    cu(s1)=y(s1)+cu(s1-1);
end
rou=round(cu);
  %temp=[0 1 2 3 4 5 6 7;re];
%temp=[rou;re];
    for o=1:t
        for l=1:s          
               for w=1:256
                   if c(o,l)==w-1
                       tem(o,l)=rou(w);
                   end          
                end
        end
    end     
    figure;
    histeq(c)
    figure;
  imshow(tem);
 figure;
 imshow(c);