pause loop with "if" statement?

Question

MSolano 2021-8-31

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1444209-pause-loop-with-if-statement

评论： MSolano 2021-9-2

Hello everyone

I'm using App Designer to do an animation with a while loop, I want the animation to pause when time reaches a value (let's say 5) I use an "if" statement to do that so I have the code below

The problem is that when I say: if (toc(t_h)-app.PauseTime) == 5 it does nothing (the animation doesn't stop)

but if I write: if (toc(t_h)-app.PauseTime) > 5 instead it does work but I don´t want it to stop in 5.01 or 4.99 I need it to stop in the exact 5

I any of you could give me a clue I would really appreciate that. Thanks!

    properties (Access = public)
        PauseTime = 0; % Description
        PauseHandle = tic;
    end
  
    % Callbacks that handle component events
    methods (Access = private)
        % Button pushed function: StartButton
        function StartButtonPushed(app, event)
            
            close all
            set(app.StartButton,'Text','Restart')
            time = 60;                                            
            set(app.UIAxes, 'units','points')
            cla(app.UIAxes);
            cla(app.UIAxes2);
            
            R = 65;  
            ang=linspace(0,2*pi,50);              
            xp=R*cos(ang);                        
            yp=R*sin(ang);  
                        
                % Animation
                
                % Draw outter circle
                patch(app.UIAxes,xp,yp,'w')
                hold(app.UIAxes,'on');
                hold(app.UIAxes2,'on');
                axis(app.UIAxes, 'equal');
                f = 0.016;
                Nb=10;
                
                % Balls
                rho1 = 55; 
                n = linspace(0,360,Nb+1);
                line = plot(app.UIAxes,NaN,NaN,'o', 'LineWidth', 1, 'MarkerSize', 15, 'color', 'k');
                
                % Mark on 1st ball
                mark = plot(app.UIAxes,NaN,NaN,'*', 'LineWidth', 1, 'MarkerSize', 5, 'color', 'r'); 
                
                % Fixed Mark
                plot(app.UIAxes,[55 65],[0 0], 'LineWidth', 5,'color','r');
                
                % Sine Wave
                % Static
                Swx = linspace(0,time,time*100);
                Swy = (pi/2)*sind(360*Swx*f);
                plot(app.UIAxes2,Swx,Swy,'LineWidth', 1, 'MarkerSize', 1, 'color', 'k');
                
                % Moving point Sine Wave
                sw = plot(app.UIAxes2,NaN,NaN,'o', 'LineWidth', 1, 'MarkerSize', 5, 'color', 'r','MarkerFaceColor','r');
                                      
                t_h=tic;
                app.PauseTime=0;
                while   (toc(t_h)-app.PauseTime) < time
                
                % Balls
                t1=toc(t_h)-app.PauseTime;
                f1 = f*360;
                line.XData = rho1*cosd(n+f1*t1) ;
                line.YData = rho1*sind(n+f1*t1) ;
                
                app.Time.Value = t1;
                
                % Point on sinewave                              
                t2=toc(t_h)-app.PauseTime;
                sw.XData = t2;
                sw.YData = (pi/2)*sind(360*f*t2);
                
                % Slider
                t3=toc(t_h)-app.PauseTime;
                app.Slider.Value = t3; 
                
                % Mark
                t4=toc(t_h)-app.PauseTime;
                f1 = f*360;
                
                mark.XData = rho1*cosd(f1*t4);
                mark.YData = rho1*sind(f1*t4);
                
                if (toc(t_h)-app.PauseTime) == 5
                        PauseButtonPushed(app, matlab.ui.eventdata.ButtonPushedData)
                end
                drawnow
                
                end
                
           
        end
        % Button pushed function: PauseButton
        function PauseButtonPushed(app, event)
            app.PauseHandle = tic;
            uiwait(app.animation)
        end
        % Button pushed function: ResumeButton
        function ResumeButtonPushed(app, event)
                        
             app.PauseTime = app.PauseTime + toc(app.PauseHandle);
             uiresume(app.animation)
        end
        
        
        

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Fangjun Jiang 2021-8-31

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floating-point data equal comparison issue?

1-1/3==2/3

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Answer 1

cr 2021-9-1

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1444209-pause-loop-with-if-statement#answer_778314

You must give it a range of time period rather than a unique time point since the execution doesn't guarantee the particular line toc() will be executed at t = 5s. If you need it to stop only once try giving a shorter period.