A moving point along a graph.

Question

Ian Tee 2016-4-27

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回答： Xingwang Yong 2020-11-7

Hello everyone, i succesfully plotted a graph that looks like this. figure 1- Graph

Right now, i want to make a point move along the graph. I need some help with that, is there a simple way of making a point move along the plot?

Any help, suggestions or advice will be heavily appreaciated :D

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Answer 1

J. Webster 2016-4-27

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https://ww2.mathworks.cn/matlabcentral/answers/281305-a-moving-point-along-a-graph#answer_219667

编辑：J. Webster 2016-4-27

在 MATLAB Online 中打开

You put the plot inside of a loop and update the position of the point each time...

x = 0:.01:6;
y = sin(x);
px = 0;
py = 0;
for i=1:100
    figure(100); %This is so it will replot over the previous figure, and not make a new one.
    plot(x,y, px, py,'o');
    pause(0.1);
    px = px+6/100;
    py = sin(px);
end

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Ian Tee 2016-4-28

在 MATLAB Online 中打开

I see, i get the rough idea but i dont know how to update each plot in my case. Any more pointers will be much appreciated :)

    % Symbols needed for equation of motion and constants
h0 = 10;  % initial height
v0 = 0;  % initial velocity
t0 = 0;  % Start time
dT = 0.01; %rate of change of time, step size
Tend = sqrt(h0)*2; %time when balls stop bounce
g  = -9.81; % Constant, gravity
Friction = 0.4; %To allow dampening, value chosen from trial and error
Time=t0:dT:Tend; %Start time to end time with step size of 1/1000
Height = size(Time);
%Iteration of dx to simulate  drop  using equation of motion
%eq (1) : x=x+v+1/2*g*t
for iX= 1:length(Time) 
     H1= h0 + (v0*dT) + (g*dT^2*0.5)*dT; %equation of motion (1)
     v0=v0+g*dT; % step size for the change of velocity with time
     %disp(H1)
     %disp(v0)
     %used to predict graph
       if H1<0 ;
       H1=0; %ball hits ground
       v0=-v0*sqrt(Friction); % 'refresh' size of curve to simulate lost of energy
       end
    Height(iX)=H1; %index of height for each value of time
    h0=H1;%couple with friction to start smaller curve with lower new Height
  end
  plot(Time,Height)