This code tests rising edges plus the time they occured, but it still give me errors, plus it has to check the file line by line.....PLEASE HELP

function [l,c,n] = find_edges(s , a, file)
fid = fopen(file, 'r'); disp('found');

      v1 = [0 0 0];
      v2 = [0 0 0];
      v3 = [0 0 0];
     b = false;
      seq_dur=0;
      seq_dur = seq_dur + 1;  
     
      act_off = 0;
  last_t = 1 + act_off - seq_dur; l = v1; c = v2; n = v3; frewind(fid); N=fread(fid, 16, 'double'); length(N) N(1:10) assignin('base','helpme',N)

      % Set the threshold to 3.5 V.
  threshold = 3.5;
  offsetData = [fid(2:end); NaN];
  risingEdge = find(fid < threshold & offsetData > threshold);
  fallingEdge = find(fid > threshold & offsetData < threshold);
  hold on
  plot(time(risingEdge), threshold, 'rx');
  plot(time(fallingEdge), threshold, 'go');
  hold off
  pulseIndices = zeros(length(risingEdge) * 2, 1); pulseIndices(1:2:end) = risingEdge; pulseIndices(2:2:end) = fallingEdge; pulseTimes = diff(time(pulseIndices));

%c(2) = mult; %n(2) = mult;

while ~feof(fid) swap(l, c); swap(c, n); fread(fid, 'double', 16)   t = mod(c(0), seq_dur) - 1; n(2) = mult;

            if(~b && l(2) > 0.4 && c(2) > 0.9 && n(2) > 1.0)
      
        if(~b)
            rel_delta = l(1) - last_t;
          disp( l(1), ' ' , rel_delta , ' ',  (t + (l(1) - l(1))) , ' ', l(2) , ' ');
          last_t = l(1);
          if(rel_delta > (seq_dur + 3) || rel_delta < (seq_dur - 1))
            disp( 'bad delta ');
                      disp( ' ');
                      disp(   rel_delta );
                      disp(  sprintf('\n'));
            if(~cont) 
                          break;
                      end
                  end
              end
             
        b = true;
  elseif(b && l(2) < 0.8 && c(2) < 0.5 && n(2) < 0.5) disp(t + (c(1) - c(1))); disp(sprintf('\n')); b = false;

            end
      
  end
  b = true; t=2; if(b) disp(t) disp(sprintf('\n')) end

   end

[Walter Roberson]

What errors are you observing? Is there an error message?

Why is it a problem if the code checks the file line by line?

What is swap() ?