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# A moving point along a graph.

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Ian Tee on 27 Apr 2016
Answered: Xingwang Yong on 7 Nov 2020
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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### Answers (2)

J. Webster on 27 Apr 2016
Edited: J. Webster on 27 Apr 2016
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 on 28 Apr 2016
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)

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Xingwang Yong on 7 Nov 2020
Although this is an old thread, in case someone needs, ##### 0 CommentsShowHide -1 older comments

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