MATLAB: Ho we run a section code one time in Matlab function block ? In below body I dont want assigning zeros in Dout after 1st iteration. This matlab function block run 100 times and problem is it every time set zeros in dout.

Question

function y = ADC(u, clk, count)
%function y = fcn(u, clk)
count=count+1;
% if clk==1
%     disp('hello');
% end
% emulation of SAR ADC operation
Nbit = 7; 
Vref = 64;
VCM = Vref/2;
%dVin = (-37298:37299)/37299*Vref;
Point=u;
dVin = (-Point:Point)/Point*Vref;
%plot(dVin);
Vip = dVin/2+VCM;
Vin = -dVin/2+VCM;
N = length(dVin);
k=count;
*Dout = zeros(1,N);
B = zeros(1,Nbit);*
   while k <=N          
          if clk==1
              Vxp = Vip(k);
              Vxn = Vin(k);
              for kbit = 1:Nbit
                  if Vxp - Vxn > 0
                      B(kbit) = 1;
                      Vxp = Vxp - Vref*2^(-kbit);
                  else
                      B(kbit) = 0;
                      Vxn = Vxn - Vref*2^(-kbit);
                  end
              end
              Dout(k) = B(1)*64 + B(2)*32 + B(3)*16 + B(4)*8 + B(5)*4 + B(6)*2 + B(7)*1 -64 +0.5;
            %  k=k+1;
             break;
          else
             %k=k+1;
             break
          end
      end
plot(dVin,Dout,'r*')
y = Dout;

Answer 1

You can make Dout persistent so it preserves the value between runs, like this

persistent Dout;
if isempty(Dout)
  Dout = zeros(1,N);
end

HTH