radix 2 dis in frequency

for K=0:7
    for N=0:3
        if mod(K,2)==0
            v(N+1)=(x(N+1)+x(N+5))*exp(-1i*N*K*pi/2);
        elseif  mod(K,2)==1
             v(N+1)=((x(N+1)-x(N+5))*exp(-1i*N*pi/4))*exp(-1i*N*K*pi/2);
       end
      end
  Y(K+1)=sum(v);
  end

i assume that is radix 2 disspation in frequency what's wrong in it

[Walter Roberson]

duplicate is http://www.mathworks.co.uk/matlabcentral/answers/55824-radix-2-disspation-in-frequency