Identify missing section's boundaries in an index

dear matlab community, I started working with matlab about a month ago so I am still a beginner and this question might (I hope) have a very easy solution.

I working on large arrays (2000000 points) and for an analysis I am extracting only specific parts of it. When I extract the data I want to work with I get an vector of the indexes of the point I need, something like:

index=[1,2,...,412,413,1265,1266,...,2874,2875,9654,9655,...]

and I want to get something like: B={[413 1265][2875 9655]} or any way to identify both ends of the missing part.

so far i have tried to use diff but it doesnt return the upper limit and the whole thing isn't really working! I hope that you can understand what I want to do and find a solution. I'm adding here things I've been trying but it not an actual script just bits of it...

index_b=find(data_v < (-0.06));             %condition
k_b=time_v(find(diff(index_b) > 1))';         %get lower index
A_b = cell(1, length(k_b)+1);                 %prealloc
for i = 1:length(k_b)
  A_b{i} = index_b(count_b+1:k_b(i));       %creat cell array
  count_b=k_b(i);
end
t_b=[];
for i= 1:length(A_b);                         %merge the cells
  t_b=[t_b,A_b{i}];
end
time_b=time(t_b);

Answer 1

[Greg Dionne]

Do you just want all the elements less than -0.06?

Then

data_v(data_v < -0.06)

should give you want you want.

If you need a single range you can do:

data(istart:istop)