How to get original values from cumulative sum values?

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I have a list of cumulative sum values. I want to obtain another list with the values that generated the cumulative sum vaues. Something like a reverse cumulative sum process. I tried (X2-X1) formula for each consecutive value but couldn't get the exact values. Can someone please help me to reverse the cumulative sum values to original values.
Thank you

Accepted Answer

Stephen23
Stephen23 on 19 Jun 2022
X = rand(1,9)
X = 1×9
0.8615 0.8710 0.7907 0.5073 0.3673 0.4523 0.4018 0.2258 0.1596
Y = cumsum(X)
Y = 1×9
0.8615 1.7326 2.5233 3.0306 3.3979 3.8502 4.2520 4.4778 4.6374
Z = [Y(1),diff(Y)]
Z = 1×9
0.8615 0.8710 0.7907 0.5073 0.3673 0.4523 0.4018 0.2258 0.1596
max(X-Z) % alomsot zero
ans = 4.4409e-16
Because of the accumulated floating point error getting exactly the same values is not expected.

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