I have a .mat file that is a 2x1000 matrix. I want to get the 2 rows as data that I can imput into cftool. How would I go about this?

This the the file. How would I be able to imput this data into cftool so that it creates an ocilating graph?

Answer 1

[Mathieu NOE]

hello @Dakota

FYI, a simple code that does not need any special toolbox :

load('Data.mat')
Time = mat(1,:);
Data = mat(2,:);
    
    %% fit  data 
    [b,yf] = exp_decay_sinus_fit(Time,Data);
    % b array contains 5 coefficients according to this equation (model)
    % y = b(1).*exp(b(2).*x).*(sin(2*pi*b(3)*x + b(4))) + b(5)
    eq_str = [ ' y =  ' num2str(b(1),'%.2f'),'* exp(-' num2str(-b(2),'%.2f') ' t) * sin(2*pi*' num2str(b(3),'%.2f') ' t + ' num2str(b(4),'%.2f') ' ) + (' num2str(b(5),'%.2f') ')'];
    figure
    plot(Time,Data,'*',Time,yf,'r','linewidth',2);
    legend('data',eq_str);

%%%%%%%%%%%%%%% functions %%%%%%%%%%%%%%%%%%%%%%
function [B,yf] = exp_decay_sinus_fit(t,y)

    [yu,indm] = max(y);
    yl = min(y);
    yr = (yu-yl);                                                                   % Range of y
    yz = y-yu+(yr/2);
    
    % zero crossing (period / freq estimation)    
    zt = t(yz(:) .* circshift(yz(:),[1 0]) <= 0);                                   % Find zero-crossings
    per = 2*mean(diff(zt));                                                         % Estimate period
    freq = 1/per;                                                                   % Estimate frequency
    
    % initial phase estimate 
    tmax = t(indm);
    phase_init = mod(-2*pi*freq*tmax + pi/2,2*pi);                                  % initial phase estimate 

    ym = mean(y);                                                                   % Estimate DC value (offset)
    fit = @(b,x)  b(1).*exp(b(2).*x).*(sin(2*pi*b(3)*x + b(4))) + b(5);             % Objective Function to fit
    fcn = @(b) norm(fit(b,t) - y);                                                  % Least-Squares cost function
    B = fminsearch(fcn, [yr; -0.1;  freq;  phase_init;  ym]);                       % Minimise Least-Squares
    if B(4)<0 % complement negative phase with 2pi
        B(4) = B(4) + 2*pi;
    end
    yf = fit(B,t);

end