Numerical integration of voltage over time

I have the vectors of time (T) and voltage (V).

According to the following expression:

    % integral from 0 to t of voltage V in dt = k * i (t)

where:

k = known constant; (unit measure: A*V^-1*s^-1)

i(t) = current intensity as a function of time.

How can I numerically integrate in Matlab the voltage V to get i(t)?

Answer 1

[Star Strider]

I would use the cumtrapz function.

[Quong Axxong]

Thank you for your quick answer!

The only problem that I have got is that the resulting current intensity curve is tilted as you can see in the attached figure.

How can I align it to the x-axis?

[Star Strider]

My pleasure!

I don’t have your data, but I would guess that the tilt is due to a constant offset that is integrating (as expected) to be a linear function of time, and added to your integrated signal.

I would subtract the median from your voltage signal before integrating it:

Vcorr = V - median(V);

I would subtract the median rather than the mean, because the mean is affected by extreme values, while the median is not.

If that doesn’t work, the other option is to use the detrend function on the integrated signal.

[Quong Axxong]

It worked with median.

Thank you so much, you have been very helpful with both answers!

[Star Strider]

As always, my pleasure!