# for loop. finding the right index

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Ireedui Ganzorig on 18 Mar 2020
Commented: Ireedui Ganzorig on 18 Mar 2020
Hello MATLAB community,
stateOfEnergy is a bunch of data in a column, and I found the largest increase and decrease of stateOfEnergy by utilizing the for loop and built-in <max> and <min>. But I am really struggling to find indices where the largest increase and decrease occured. Below is my code. Is therer any way you can find that specific indices?
stateOfEnergy = load('40815SOE.csv'); % in kiloWattHour
for i = 2 : length(stateOfEnergy)
changeInSOE(i-1) = stateOfEnergy(i) - stateOfEnergy(i-1);
end
largestIncrease = max(changeInSOE); % largest increase of change in SOE in invertal of a single minute. in kWh
disp(['The Largest Increase in SOE was ', num2str(largestIncrease), 'kWh was found between index', ])
largestDecrease = min(changeInSOE); % % largest decrease of change in SOE in invertal of a single minute. in kWh
disp(['The Largest Decrease in SOE was ', num2str(largestDecrease), 'kWh was found between index', ])

David Goodmanson on 18 Mar 2020
Edited: David Goodmanson on 18 Mar 2020
Hello Ireedui,
max and min find the indices as well as the values.
changeInSOE = diff(stateOfEnergy) % find all the differences
[valmax indmax] = max(changeInSOE)
[valmin indmin] = min(changeInSOE)
indmax = n says that the largest positive change of value = valmax occurred from stateOfEnergy(n) to stateOfEnergy(n+1).
indmin = m says that the largest negative change of value = valmin occurred from stateOfEnergy(m) to stateOfEnergy(m+1).
Ireedui Ganzorig on 18 Mar 2020
Thank you very much. You explained it very well. I got it. Thanks.