How to save vectors with different lengths in a matrix?

For research project I want to calculate damping factor of a oscillation, that occur multiple times over time. With the wavetimecheck, I compute the time of the wave 1,2,3... were in the oscillations occur. with peakdet I find the peaks of the force and time. from the plot i can see that there are 5 peaks, so I let it run to n=4. Fist i forget to save the values of timeup1 forceup1, so I calculated only one dampingfactor. Now I want to save these values in a matrix, but these wavetimes differ, so the length of the vectors "timeup" and "forceup" of oscillation 1 and oscillation 2 are different. So I want to save these vectors in 1 matrix, I think that is the most handy way to calculate the damping factor. Or is there a more easy way?

This is the code I wrote.

for m = 1:30

timeup = wavetime_check(m,1):wavetime_check(m,2);

MATtime(m,:) = timeup;

format long

forceup = (force_filt((wavetime_check(m,1)):(wavetime_check(m,2))).');

MATforce(m,:)= forceup

[maxtab, mintab] = peakdet(forceup, 0.0000001, timeup);

for n = 1:4 % heeft 5 peak dus n tot 4.

logdec (n) = log(maxtab(n,2)/maxtab((1+n),2))

end

Mean_logdec = mean(logdec)

Zeta= Mean_logdec/sqrt(4*(pi)^2 + (Mean_logdec)^2)

end

Answer 1

[Ameer Hamza]

You cannot use a matrix to store vectors of varying length. For that, you will need to use a cell array. Use it as follow.

timeupMatrix{m} = timeup;
forceupMatrix{m} = forceup;

You can access them using timeupMatrix{1}, timeupMatrix{2} notation.

[Kevin Paapst]

Ahh thankyou! That part works now! Now I think I have a similar problem. I changed my code and to compute the peaks i know have:

[maxtab, mintab] = peakdet(MATforce{m}, 0.00000007, MATtime{m})

It computes/find now all the peaks, but only saves the last values of the peaks, for m=30, and so only calculates the damping factor for m=30.

How can I save the values of [maxtab,mintab] also in an cell array?

[Ameer Hamza]

You can use

[maxtab{m}, mintab{m}] = peakdet(MATforce{m}, 0.00000007, MATtime{m})