im a little confused on how I can get this to work I've changed the index size and nothing seems to work can someone help me pls. I keep getting error "Index exceeds matrix dimensions." i get the error @ for i = 1:3 m(i) =(.25*out(i,6) - .5...

clc close all dataTable = zeros(6,5); % matrix for n = 1:6 if n <= 3 fileName = ['trial',string(n),'.25kg.txt']; fileName = fileName(1) + fileName(2) + fileName(3); else fileName = ['trial',string(n),'.5kg.txt']; fileName = fileName(1) + fileName(2) + fileName(3); end % Use your data file here (keep it in the same folder): fid = fopen(fileName, 'r' ); fgets(fid); % to get rid of the first 2 lines. do not change! fgets(fid); n=1; datmat=[]; % Initialize an empty string while 1, a= fgetl(fid); % Read one line of data in at a time in the format of a STRING if n == 1, na=length(a);, end; if ~isstr(a), % If a is no longer a string, stop reading break; end; n=n+1; anum=eval(['[',a(2:na-1),']']); datmat=[datmat;anum]; % mas is the data matrix end

A=datmat(:,4);
if A>0
  B=A+A(677);
else
  B=A-A(677);
end
datmat(:,4) = B;

    [N,M]=size(datmat);                 % Dimensions of the matrix

    %   Descriptions of the columes:
    %       M=1, the sample index, sample index starts from 0
    %       M=2, the real time in seconds
    %       M=3, the excitation signal
    %           the force conversion factor to physical units = ??
    %       M=4-6, the readings from encoders 1-3
    %           the encoder conversion factor to physical units = ??
    %

    %   Algorithm for identifying the peaks of the motion

    m=4;                % Look at the first encoder

    for n=1:N,
       if datmat(n,m) ~= 0,
          firstsign=sign(datmat(n,m));
          ns=n;
          break;
       end
    end

    peak=[];                            % The variable to hold the peak values
    neak=[];                            % The corresponding index of the peak value
    numk=5;                             % Number of peaks to look for

    for npk=1:numk,

        for n=ns+1:N,
           nsign=sign(datmat(n,m));
           if nsign ~= firstsign,
              ns2=n;
              break;
           else          %if signs dont change find last peak
               if n == N
                  ns2 = n;
               end
           end        
        end

        [ak,nk]=max(abs(datmat(ns:ns2,m))); % ak is the peak value in the range ns:ns2, nk is its index
        peak=[peak,ak*firstsign];
        neak=[neak,ns+nk-1];

        ns=ns2;                             % Get ready for next peak search
        firstsign=nsign;

        if ns >= N-1, 
            break; 
        end

    end

    figure 
    plot(datmat(:,1),datmat(:,m))
    hold on
    plot(neak-1,peak,'x')
    xlabel('Time (s)');
    ylabel('Encoder position');
    legend('Response', 'Peaks')

    t = datmat(neak,2);%time

    p = t(4)-t(2);             %period
    d = log(peak(2)/peak(4));   %log decrement
    c = (2*d)/p;                %damping constant/mass
    wd = (2*pi)/p;              %damped frequency
    wn = sqrt(wd^2 + c^2/4);    %natural frequency 
    k = wn^2;                   %spring constant/m
    s = d/(wn*p);               %damping ratio

    out(j,:) = [s,wn,wd,d,p,k,c,0]    %place all variables in matrix for output

end

for i=1:3 m(i)=(.25*out(i,6) - .5*out(i+3,6))/(out(i+3,6)-out(i,6)); %calculate three mc values end

mc = mean(m); %mc = average of ratio values

out(1:3,8)= .25 + mc; % actual mass = mass added plus mass of the cart out(4:6,8)= .5 + mc;

out(:,6) = out(:,6).*out(:,8);%multiply k/m by mass to get final k value out(:,7) = out(:,7).*out(:,8);%multiply c/m by mass to get final c value

display(out)

[Walter Roberson]

Some of the code is missing. We do not know that out has at least 6 rows.

Also, it is not impossible that some of those variables you are storing are empty, resulting an an out matrix that is not at least 6 wide.