take a sum in a matrix and print it on a different row

process time start time end time

2 0

1

3

6

Suppose I have such a matrix.

I want to make start time + process time and find the end time. For example, the end time of the first row is 2.

then i want to do this:

The start time of the second row = the end time of the first time

End time of second row = end time of first row+process time of second row

For example :

process time start time end time

2 0 2

1 2 3

3 6 9

6 9 15

How can I do this for a large matrix?

Thank u for help

Answer 1

[Matt J]

proctime=[2 1 3 6];
n=numel(proctime);
endtime=cumsum(proctime);
starttime=[0,endtime(1:n-1)];

table(proctime',starttime',endtime','Var',{'Process Time','Start Time', 'End Time'})

ans = 4×3 table
    Process Time    Start Time    End Time
    ____________    __________    ________

         2              0             2   
         1              2             3   
         3              3             6   
         6              6            12   

[Berfin Çetinkaya]

Thank you for help!

Answer 2

[Torsten]

A = process time vector (as a column vector)
B = zeros(numel(A),3);
B(:,1) = A(:,1);
C = cumsum(B(:,1));
B(2:end,2) = C(1:end-1);     
B(:,3) = C(:);       

[Berfin Çetinkaya]

Thank you for help!

Answer 3

[Voss]

If you are starting with an Nx3 matrix of (process, start, end) times:

% initial matrix:
%  process start end
times = [2   0 NaN; ... % doesn't matter what the elements where I have NaNs are initially.
         1 NaN NaN; ... % they will be overwritten.
         3 NaN NaN; ...
         6 NaN NaN];

% fill in the remaining start times:
times(2:end,2) = times(1,2)+cumsum(times(1:end-1,1))

times = 4×3

2 1 NaN 1 3 NaN 3 4 NaN 6 7 NaN

% fill in the end times:
% end time = start time + process time
times(:,3) = times(:,2)+times(:,1);
disp(times);

     2     1     3
     1     3     4
     3     4     7
     6     7    13

Or if you are starting with a single initial start time and a vector of process times:

% initial start time:
initial_start_time = 0;
% vector of process times:
process_time = [2; 1; 3; 6];

% calculate the end times:
end_time = initial_start_time+cumsum(process_time);
% the (i+1)th process starts when the ith process ends:
start_time = [initial_start_time; end_time(1:end-1)];

% put everything together in a matrix:
times = [process_time start_time end_time];
disp(times);

     2     1     3
     1     3     4
     3     4     7
     6     7    13

[Berfin Çetinkaya]

Thank you for help!

[Voss]

You're welcome!