Using Trapz/Cumtrapz- what is unit spacing

I'm using the cumtrapz and trapz functions, and integrating from acceleration to get a displacement value. The data is collected over even time intervals for 120 data points. I'm simply not sure I understand what is meant by "unit spacing". I don't know if I should be dividing the integral by 120 or not.

%Should my code read something like:
vel = cumtrapz(acc)/120 %where acc = <120x1 double>
disp = trapz(vel)/120 %from above, vel = <120x1 double>

I feel that because the spacing between points is a time instant which is constant you don't need to be dividing by 120 but perhaps I am wrong?

Could someone please clarify for me what "unit spacing" means and when you would use a spacing increment.

Answer 1

[Matt J]

trapz(Y) and cumtrapz(Y) assume the spacing between your time samples Y(i) is 1. If it is not 1, you should multiply the result by the spacing you want.

[Annemarie]

Thank you, just to clarify, therefore if you multiplied the cumtrapz(acc) by a specific spacing increment, you would need to also multiply the traz(vel) by the same spacing increment? (ie the spacing of the vel is not being set to 1 through the use of cumtrapz).

[Matt J]

Yes, all integration operations need to be told their spacing increment.