If statement to plot sections of simpsons 1/3 method only plots one area.

I'm currently designing a GUI in matlab and I need to plot the areas of iteration using the simpson's 1/3 method. The problem is, every time I go to plot the areas, only one iteration of the method get's plotted. When I was developing the code in a normal function, I would have to click run twice in order to plot all the areas. How can I fix this so it plots everything in one go?

if app.MethodEditField.Value == 3 % Simpsons 1/3
    % Simpsons 1/3
    if rem(length(x), 2) == 0
        %Display error lamp
        app.RedincompatableamountofdatapointsLamp.Color = [1 0 0];
    else
        % define starting values
        Area = 0;
        b = 0;
        % create for loop to pull from the given data points
        for i = 1:2:length(y)-2
            I(b+1) = b;
            A(b+1) = Area;
            % define deltax
            v = x(i+2)-x(i);
            % add the area to itself along the for loop
            Area = Area + ((y(i)+4*y(i+1)+y(i+2))/6)*v;
            b = b + 1;
            % end the for loop
        end
        % Final I and A values
        I(b+1) = b;
        A(b+1) = Area;
        Area = num2str(Area);
        app.AreaEditField.Value = Area;
        hold on                                         % Start graphing
        %figure(app.UIAxes_2)                                       % Call figure 1
        plot(app.UIAxes_2,I,A,"-",'LineWidth',2,'Color',[0 0 0])     % Plot area per iteration
        title(app.UIAxes_2,'Area Increase Per Simpsons 1/3 Area')     % Title figure 1
        xlabel(app.UIAxes_2,'Iteration')                             % Label x Axis
        ylabel(app.UIAxes_2,'Area')                                  % Label y Axis  
        
    end
    plot(app.UIAxes_3,x,y,"-",'LineWidth',2,'color',[0 0 0])                                                                   %plot function
    title(app.UIAxes_3,'Simpsons 1/3 Integration Method')                                         % Title plot
    xlabel(app.UIAxes_3,'x')                                                                     % Label x axis
    ylabel(app.UIAxes_3,'y')                                                                     % Label y axis  
    %figure(app.UIAxes_3)                                                                       %call second figure
    for i = 1:2:length(x)-2                                                         %for loop to 
        % Plot the polygon
        plot(app.UIAxes_3, polyshape([x(i),x(i+1),x(i+2),x(i+2),x(i)],[y(i),y(i+1),y(i+2),0,0]))
        hold on
    end
    hold off
end

[Rajeev]

Can you try removing the hold off statement from the second last line?

[MATLABC]

It still only shows one iteration of the for loop :/

Answer 1

[Rik]

Without explicit handles, most graphics functions revert to the normal figures. You should try providing the handle to your uiaxes, or set its nextplot property directly.