Help me understand this code please

I do understand the first step so dont explain it. Just need to understand 2nd step line by line where a diffusion key is created using logistic map.

First Step:

r = 3.62;
x(1) = 0.7;
row = size(img,1);
col = size(img,2);
s = row*col;
%Creation of Logistic function
for n=1:s-1
    x(n+1) = r*x(n)*(1-x(n));
end

2nd Step:

%Creation of diffusion key
p=3.628;
k(1)=0.632;
for n=1:s-1
    k(n+1) = cos(p*acos(k(n)));
end
k = abs(round(k*255));

ktemp = de2bi(k);
ktemp = circshift(ktemp,1);
ktemp = bi2de(ktemp)';
key = bitxor(k,ktemp);

%Ending creation of diffusion key

Answer 1

[KALYAN ACHARJYA]

First Step:

r = 3.62; % Define r
x(1) = 0.7; %define array index 1=0.7
row = size(img,1);   %Finding row size of img
col = size(img,2);   %Finding colm size of img
s = row*col;         %s=row*colm
%Creation of Logistic function
for n=1:s-1         % Loop n=1 to s-1
    x(n+1) = r*x(n)*(1-x(n));  % First x(2), x(1 is already defined), to find x array
end

2nd Step:

p=3.628;  % Define p
k(1)=0.632; %define array k index 1
for n=1:s-1  % Loop n=1 to s-1
    k(n+1) = cos(p*acos(k(n)));  % First k(2), k(1 is already defined), to find k array
end
k = abs(round(k*255));  % Multiple k with 255, then roundoff, and consider absolute
ktemp = de2bi(k);       % decimal to binary k to Ktemp
ktemp = circshift(ktemp,1);  % One bit circular shift of K temp
ktemp = bi2de(ktemp)';     % Binary to decimal , replace k temp
key = bitxor(k,ktemp);    %key= xor opeartion between k and ktemp

The application, ask the coder who done the code.

[Nazish]

Thanks alot.

for n=1:s-1

k(n+1) = cos(p*acos(k(n)));

end

I want to know what is actually happening in this for loop.

Secondly why are they doing this.. decimal to binary then binary to decimal again.

k = abs(round(k*255));

ktemp = de2bi(k);

ktemp = circshift(ktemp,1);

ktemp = bi2de(ktemp)';

[Fawad Masood]

It is simply 1 bit circle shift of element to add confusion in the generated array.