If i have a graph that levels off, how can i find the first x value this occurs at, on matlab?

Question

Aisling Laverty 2017-12-15

回答： Image Analyst 2017-12-15

I have a temperature VS time graph, and am looking for the first time(x) at which it levels off at a certain temp (y).

Birdman 2017-12-15

Can you share your code?

Aisling Laverty 2017-12-15

it was generated on simulink. i wondered if this would work?

Tstarfinal520= T_star_5_20(end); boundary520t=0.999*Tstarfinal520; %because it never is at dy/dx=0, so 99.9% should be ok.

place=find(T_star_5_20>=boundary520t); leveltime520t=tout(place(1))

Answer 1

KL 2017-12-15

It depends on how you've stored your data. Let's you have them in a matrix,

 data = [(1:10)' zeros(10,1)];
 data(5,2) = 10;
 data =
   0
   0
   0
   0
   10
   0
   0
   0
   0
   0

Let's say column 1 is time and 2 is temperature. I want to find the time when tepmerature is 10,

 t = data(data(:,2)==10,1)
 t =
     5

Answer 2

Image Analyst 2017-12-15

Perhaps use findchangepts().

Or use movstd() or stdfilt() and find the last element where the standard deviation in a window falls below a certain level.