How to extract #F-1 submatrices (dim VariableXN) from A MXN when the subset boundary values are stored in B (dimFXN)

I think the immage can describe easily my problem.

I have a single *.txt file with multiple records, from an MPU6050 connected to Arduino.

I can recognize when a new record was made because the column time restart from a random value lower then the previous (is never 0).

The file is a nX7 which contains in order time, ax, ay, az, gx, gy, gz

I defined, thanks to stack, my B matrix, where are stored all the boundary values (FXM in my pic)

I am trying to extract the F-1 submatrices from the single matrix, but each submatrix has different row, that depends from the length of the time record (A-B number of rows is different from B-C, but they have the same number of columns)

I have studied the "Submatrix" function, but i don't know how to apply in my specific situation, and i am not pratical with "Indexing" but i am studing how it works

Here the code i wrote

%Open the file 
filename= uigetfile ('.txt');
fileID = fopen (filename);
logmpu6050 =csvread(filename);
fclose (fileID); 
n=length(logmpu6050);


%Save the position of every i raw every time happens time(i)>time(i+1)
rangematrix = logmpu6050(diff(logmpu6050(:,1)) < 0,:);
%The last value sampled is exctracted from the dataset, because the last value don't satisfy the condition t(i)>t(i+1)
%but is still a boundary value
endlog=logmpu6050(end,:);
%We need to take the last  
rangematrix = cat(1,rangematrix,endlog)
lengthrangematrix = length(rangematrix);

Here is were i am stuck

for i = 1: lengthrangematrix-1

submat(i)= submatrix(logmpu6050[rangematrix(i),:]);

Thanks, always, for your time.

I also read this question and documentation, but i still not able to find the solution :/

Matrix Indexing Create Function Handle

Function Handles

MATLAB: Extract multiple parts of a matrix without using loops