Plots aren't showing the whole array!

Hi,

I received data which I have to evaluate. The data is "nearly" the same as a square wave signal. My job as simple as it appears, is to locate those points in the array where either the values suddenly rise or suddenly drop. I did this by analysing the deriviation of the data according to x. I let that deriviation plot by Matlab, but it's only showing me those peaks with positive gradient. I investigatet my data and recognized that the x-values of negative gradients are single values surrounded by those of positive gradients. Or let me say it differently: 397 Eeements of my deriviation vector are positive and only three are negative.

What could be the problem, inducing my plot to not show those points?

[Dyuman Joshi]

"I did this by analysing the deriviation of the data according to x."

What exactly was the process of analysing? Which operations did you perform?

It would be helpful if you can attach the data you are working with and the code that you have written to analyse the data.

[Johannes Graf]

Thanks for answering, right now in the moment I was able to solve it but I will state my process. Maybe it's helpfull for others :/

I deriviated numerally by

for i=1:(length(phi_K)-1)

d_phi_K(i)=(c_z_ges(i+1)-c_z_ges(i))/(phi_K(i+1)-phi_K(i));

end

then middled phi_K by

for i=1:(length(phi_K)-1)

phi_K_opt(i)=sum([phi_K(i) phi_K(i+1)])/2;

end

Than averaged the whole of d_phi_K and looked for the values which are greater in amount than the average. Until now the code was working as fine as I expected it. But when I plotted it the problem of my question appeared.

I'd overseen, that the absolute value of the negative gradients is much smaller than the maximum of my deriviation vector. So the only thing I had to do in the end was, to change the scaling of my plot to ylim([min(d_phi_K) -min(d_phi_K)]).

[Mathieu NOE]

can you share some data and a working code ?