encrypt.asv

I try to create GUI using Matlab to code hills polygraph cipher

function cipher = encrypt(plain,rka,a,b,c,d,k1,k2)
l = size(plain);
if mod(l(1,2),2)~=0
    for i = 1 : 2 - mod(l(1,2),2)
        plain(l(1,2)+i) ='x';
    end    
end
z = a*d - b*c;
z = mod(abs(z),2);

if z == 0 
    warndlg('Sory Jack Determinannya Genap','Warning');
    %break; 
    %stop;
end
%ubah teks ke angka  
  for i = 1 : 2 : l(1,2)
      %fprintf('%s\n',rk);
      for j = 1 : 26
          if plain(i) == rkunc(j)
              x1=j-1;%fprintf('x1: %d\n',x1);
              if plain(i) == plain(i+1)
                 x2=j-1;    
              end
          elseif (plain(i+1) == rkunc(j))
              x2=j-1;%fprintf('x2: %d\n',x2);
          end
      end
      y1 = (mod((mod(a*x1,26)+mod(b*x2,26)+k1),26));
      y2 = (mod((mod(c*x1,26)+mod(d*x2,26)+k2),26));
      %fprintf('y2 dan y1: %d %d\n',y2,y1);
      
      cipher(i)=char(rkunc(y1+1));
      cipher(i+1)=char(rkunc(y2+1));
            
      %fprintf('%s\n',cipher(i));
  end
return