Saving figures in loop

I have such code. I should get plots for different parameters of rho. But I get the same picture each time

for m = 1:10
    
    rho = 1 + m; % params
    chi = 1;
    u = 31;
    f1 = @(t,i,omega) u - rho*i - chi*omega; % right part of 1st ODE
    f2 = @(t,i,omega) chi*i - chi/rho*(5/6 - chi)*omega - chi/(6*rho)*sign(omega); % right part of the 2nd ODE
    
    t0 = 0;
    tn = 5;
    h = 0.005; % step 
    n = (tn - t0)/h;
    
    i0 = 0; % init i-value
    omega0 = 0; % init omega-value
    t(1) = t0; i(1) = i0; omega(1) = omega0;
    
    for k=1:n
        i(k+1) = i(k) + h*f1(t(k), i(k), omega(k));
        omega(k+1) = omega(k) + h*f2(t(k), i(k), omega(k));
        t(k+1) = t0 + k*h;
    end
    
    om31 = load("log_031.txt");
    
    t31 = 1:size(om31);
    
    h = figure(m);
    
    hold on
    plot(t31/250 - 13.536, -om31(:,4)/7200-0.3); 
    
    title('Numerical Integration')
    txt = ['u = ' int2str(u) ', \rho = ' num2str(rho) ', \chi = ' num2str(chi)];
    subtitle(txt);
    plot(t, omega, 'b');
    legend('\omega_{aist}', '\omega_{euler}', 'FontSize', 15)
    xlabel('t', 'FontSize', 15, 'FontAngle','italic')
    ylabel('\omega', 'FontSize', 15)
    grid on
    
    
    path_name = '/home/andrei/Desktop/курсач/ЧМы/31';
    file_name = strcat('u_', num2str(u), ', rho_', num2str(rho), ', chi_', num2str(chi));
    saveas(h, fullfile(path_name, file_name), 'png');
    hold off;
    close(h)
end

[Image Analyst]

Error using load

Unable to find file or directory 'log_031.txt'.

You forgot to attach it.

[Evgeniy Barkalov]

here it is

Answer 1

[Voss]

They seem to be different to me (note the different y-limits)

for m = 1:10
    
    rho = 1 + m; % params
    chi = 1;
    u = 31;
    f1 = @(t,i,omega) u - rho*i - chi*omega; % right part of 1st ODE
    f2 = @(t,i,omega) chi*i - chi/rho*(5/6 - chi)*omega - chi/(6*rho)*sign(omega); % right part of the 2nd ODE
    
    t0 = 0;
    tn = 5;
    h = 0.005; % step 
    n = (tn - t0)/h;
    
    i0 = 0; % init i-value
    omega0 = 0; % init omega-value
    t(1) = t0; i(1) = i0; omega(1) = omega0;
    
    for k=1:n
        i(k+1) = i(k) + h*f1(t(k), i(k), omega(k));
        omega(k+1) = omega(k) + h*f2(t(k), i(k), omega(k));
        t(k+1) = t0 + k*h;
    end
    
    om31 = load("log_031.txt");
    t31 = 1:size(om31);
    
    h = figure(m);
    
    hold on
    plot(t31/250 - 13.536, -om31(:,4)/7200-0.3); 
    
    title('Numerical Integration')
    txt = ['u = ' int2str(u) ', \rho = ' num2str(rho) ', \chi = ' num2str(chi)];
    subtitle(txt);
    plot(t, omega, 'b');
    legend('\omega_{aist}', '\omega_{euler}', 'FontSize', 15)
    xlabel('t', 'FontSize', 15, 'FontAngle','italic')
    ylabel('\omega', 'FontSize', 15)
    grid on
    
    
%     path_name = '/home/andrei/Desktop/курсач/ЧМы/31';
%     file_name = strcat('u_', num2str(u), ', rho_', num2str(rho), ', chi_', num2str(chi));
%     saveas(h, fullfile(path_name, file_name), 'png');
%     hold off;
%     close(h)
end

Modifying the code to plot all in one figure for easier comparison confirms:

figure();

om31 = load("log_031.txt");
t31 = 1:size(om31);
hold on
plot(t31/250 - 13.536, -om31(:,4)/7200-0.3); 

rho_label = {};
lines = [];

for m = 1:10
    
    rho = 1 + m; % params
    chi = 1;
    u = 31;
    f1 = @(t,i,omega) u - rho*i - chi*omega; % right part of 1st ODE
    f2 = @(t,i,omega) chi*i - chi/rho*(5/6 - chi)*omega - chi/(6*rho)*sign(omega); % right part of the 2nd ODE
    
    t0 = 0;
    tn = 5;
    h = 0.005; % step 
    n = (tn - t0)/h;
    
    i0 = 0; % init i-value
    omega0 = 0; % init omega-value
    t(1) = t0; i(1) = i0; omega(1) = omega0;
    
    for k=1:n
        i(k+1) = i(k) + h*f1(t(k), i(k), omega(k));
        omega(k+1) = omega(k) + h*f2(t(k), i(k), omega(k));
        t(k+1) = t0 + k*h;
    end
    
    lines(m) = plot(t, omega);%, 'b');
    rho_label{m} = [', \rho = ' num2str(rho)];
    
end

title('Numerical Integration')
txt = ['u = ' int2str(u) ', \chi = ' num2str(chi)];
subtitle(txt);
xlabel('t', 'FontSize', 15, 'FontAngle','italic')
ylabel('\omega', 'FontSize', 15)
grid on
legend(lines,strcat('\omega_{euler}',rho_label), 'FontSize', 11, 'Location','EastOutside')

Answer 2

[Image Analyst]

You can use exportgraphics() to save the figure

baseFileName = sprintf('u_%2.2d, rho_%2.2d, chi_%2.2d.png', u, rho, chi);
exportgraphics(h, fullfile(path_name, baseFileName));