Making Cumulative Difference Calculation

Hi,

I have a parameter with a column of data like this:

RunTime:

3779024.8; 3779025.8; 3779026.8; 3779027.8; 3779028.8; 3779029.8;

I want to know how I can make another parameter which calculates the cumulative difference between the values and presents it like this:

Elapsed Time:

0; 1; 2; 3; 4; 5; 6;

Thanks,

Answer 1

[José-Luis]

Not entirely sure if that's what you meant but here goes:

data = sort(rand(10,1));
cumDiff = [0;cumsum(diff(data))];

Cheers!

[Friedrich]

Small note:

The perfomance of this pretty bad and it doesnt make any sense doing it like this. Simply subtract the first value from all others (assuming data is sorted ascending). This is approx. 20-30 times faster and give the exact same result.

>> data = (1:1000)';
>> tic,cumDiff = [0;cumsum(diff(data))];toc
Elapsed time is 0.000560 seconds.
>> tic,cumDiff = [0;cumsum(diff(data))];toc
Elapsed time is 0.000549 seconds.
>> tic,cumDiff = [0;cumsum(diff(data))];toc
Elapsed time is 0.000611 seconds.
>> tic,cumDiff = data-data(1);toc
Elapsed time is 0.000021 seconds.
>> tic,cumDiff = data-data(1);toc
Elapsed time is 0.000024 seconds.
>> tic,cumDiff = data-data(1);toc
Elapsed time is 0.000023 seconds.
>> tic,cumDiff = data-data(1);toc
Elapsed time is 0.000024 seconds.

[José-Luis]

You are right. I guess i was blinded by the wording of the question.

Cheers!

Answer 2

[Azzi Abdelmalek]

 A=[3779024.8; 3779025.8; 3779026.8; 3779027.8; 3779028.8; 3779029.8];
 result=[0  ;cumsum(diff(A))];
 disp('elapsed time');disp(sprintf('%d;',result))

[Aadil]

Thanks,

I accept this answer as well