Integration of displacement to velocity then acceleration

I want to integrate this displacement vector (jh) to get velocity and then to get acceleration.

There are multiple trials of which I need to integrate from. when i do:

%%Calculation of Velocity and Acceleration
        v= trapz (jh);
        a= trapz (v);

this gives an output for the V but not for the A. When I do cumtrapz below:

%%Calculation of Velocity and Acceleration
        v= cumtrapz (jh);
        a= cumtrapz (v);
This is a cumulative integration and this is not what I want

Answer 1

[Sean de Wolski]

Don't you mean take the derivative of displacement with respect to time to get velocity and again for acceleration?

doc diff

[Adrienne]

yes i think so, how do i use that? i just try to search it in the help and it didn't come up?

[Sean de Wolski]

A simple example:

dt = 0.01;
x = 0:dt:(2*pi);
mydisplacement = sin(x);
vel = diff(mydisplacement)./dt;
acc = diff(vel)./dt;
h = plot(x,mydisplacement,x(1:end-1),vel,x(1:end-2),acc);
legend('displacement','velocity','acceleration')

[Adrienne]

i still don't know what i've done wrong:

dt=tof*[1:1:jh];
        x= (data(:,5));
        y= (data(:,5));
        vx= diff(jh)./dt;

[Sean de Wolski]

I would guess you would want dt to be a column vector so it's the same shape and size as x and y and you will want to have it be the change in time, not absolute time.