Designing a Nth butterworth filter with plot placement

 I am trying to design a Nth order continous time Butterworth filter in state space, with pole placement technique.

n = varargin{1}
Fc = this.fc 
wc = 2*pi*Fc;
T = 1/(2*pi*Fc);
%----------------Finding Poles--------------------------
 p = exp(1i*(pi*(1:2:n-1)/(2*n) + pi/2)); %n is the order of the filter
                 p = [p; conj(p)];
                 p = p(:);
                 if rem(n,2)==1   % n is odd
                     p = [p; -1];
                 end
%----------------Finding Filter co efficents---------------
                 if length(p)<= 2
                    a = conv([1,-p(1)],[1,-p(2)]);
                end
                if length(p) > 2
                    a = conv([1,-p(1)],[1,-p(2)]);
                    for i = 3: length(p)
                        a = conv(a,[1,-p(i)]);
                    end
                end
                a = real(a)
                a = fliplr(a);
%----------------- calculating the matricies%-----------------

              %--------------A matrix---------------
              N = length(a)-1;% order of the matrix
              last_row = (a(1:end-1))*(-1/a(end));% creating the last row

               last_row = (wc.^(N:-1:1)).*last_row;% creating the last row

              k = ones(1,N-1);
              this.x = diag(k,1) ; % diag(vector, k) produce a matrix filled with zero's and k'th off diagonal as vector, in this  case, 1's.
              this.x(end,:) = last_row;% adding the last_row

              %-------------desiging B matrix--------------
              this.y = zeros(N,1); % creates a coloumn matrix with zeros
              this.y(N,:) = 1/(a(end)*wc^n); % writes last elements as a

              %--------------- writing C matrix--------------
              this.z = zeros(1,N); %creates a row matrix
              this.z(1,1) = 1;

              %------------ writing the D matrix----------------

              this.u = [0];

I know the code is bit lengthy, but i have tried everything, but can't figure out where i am going wrong. Because I am not getting any error. The resultant output is just 0. The code is pretty simple, I find the poles, then the filter coefficients. With the filter coefficients, i design A,B,C,D Matrices. This is a continuous butterworth filter, Can anyone point the mistake i am doing?