Can't seem to understand what my mistake is (Loading .mat files)

So I had saved .mat files from my 2 Matlab codes and now loading into a new Matlab File for a comparison plot!

But I am getting an error that it is an "unrecognized function or variable", when I can clearly see the variable in my workspace

All the files ae attached!!

clear all;
close all;
clc;

% Comparison Plot

filenames = {'q_Theta_Y.mat','q_dot_Theta_Y.mat','q_Y_Theta.mat', 'q_dot_Y_Theta.mat',...
             'q_ref.mat', 'q_ref_dot.mat', 'Time.mat',...
             'E_pos_Theta_Y.mat','E_vel_Theta_Y.mat','E_pos_Y_Theta.mat', 'E_vel_Y_Theta.mat'};  
for kk = 1:numel(filenames)
    load(filenames{kk})
end

%--------------------------------------------------------------------------
%%%%%%%%%%%%%%%%%%%%%%%% Plot results %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%--------------------------------------------------------------------------
    % Plot Comparison b/w q_ref1 and q1 (Position of Link 1)
    set(figure,'Color','white')
    subplot(2,2,1)
    plot(Time,q_Theta_y(:,1),'b-',Time,q_ref(:,1),'k-.','LineWidth',2);
    grid on
    grid minor
    hold on
    plot(Time, q_Y_Theta(:,1), 'r-', Time,'LineWidth',2);
    axis tight
    title('Link 1: actual and reference trajectory', 'fontsize', 20);
    xlabel('$$t \, {\rm [s]}$$', 'interpreter','latex','fontsize', 20);
    ylabel('$$Position (m)$$', 'interpreter','latex', 'fontsize', 20);
    % xlim([0 t_net(length(t_net))]);
%     ylim([-1.2 1.2]);
    legend('$$q_1$$($$\Theta \cdot Y$$)', '$$q_{1,{\rm ref}}$$', '$$q_1$$($$Y \cdot \Theta$$)',...
            'interpreter','latex','fontsize',25);
    hold off

[Stephen23]

@Japnit Sethi : please show us the complete error message. This means all of the red text.

Why are you saving one variable per file? Your code would probably be simpler if you saved all of those variables in one file (tip: use the -struct option when saving, and always load into an output variable. Note that load also lets you select which variables to import from the file).

Answer 1

[Stephen23]

The bug is very simple: your code refers to

q_Theta_y

but the variable in the mat file is named

q_Theta_Y

You need to use the correct case (variable names are case-sensitive).

Much better would be to replace all of those separate files with one mat file and load into an output variable (which is a scalar structure), e.g.:

F = absolute or relative path of the mat file.
S = load(F);

Note that you can select which variables you want to import, e.g.:

S = load(F,'Time','q_Theta_Y');

[Japnit Sethi]

Thanks I'll try doing it with a single struct!!