MATLAB: Minimum of a vector or array

matlab function

Hi, i am new to a matlab at all and have a question. so i had been given an excel file with a lot if data in it. so now i need to find minimum of a vector or array from each of the column but dont know how to do it 🙁 if anybody can help me in explaining it step by step it would be much appreciated! thanks!

Best Answer

First, use the xlsread function to import the data, then then min function to find the minimum.

For example:

Data = xlsread('file_name.xls');
[ColMin,RowIdx] = min(Data);

This would import your data, then find the minimum value of the column and the row of the first instance of the occurrence of that value. (If you want to search for more than one instance of the minimum value, use the find function.)

NOTE — This is obviously UNTESTED CODE. It should work but I’ve not tested it with your file.

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Use the max and min functions with two outputs to get the first instance of the maximum and minimum. Then use the second (index) output to find the value of time where it occurred:

[ymax,maxidx] = max(y);
[ymin,minidx] = min(y);
figure(1)
plot(time, y)
hold on
plot(time(maxidx), ymax, '^r')
plot(time(minidx), ymin, 'vr')
hold off
grid

If you have more than one values for the maximum or minimum, use the find function:

maxidx = find(y == max(y));

and the plot calls then change to:

plot(time(maxidx), y(maxidx), '^r')

and the same for the minima.

NOTE — This is UNTESTED CODE but should work.

MATLAB: In an assignment, number of elements in A and B must be same

This line:

mins(t) = find(R(:,t)==min(R(:,t)));

will return all indices equal to ‘min(R(:,t))’. Apparently, there are more than one. If you want to return all of them, the easiest way is to do that is to use a cell array for ‘mins’:

mins{t} = find(R(:,t)==min(R(:,t)));

If you only want the index of the first minimum in the column, you can also just use the min function:

[~,mins(t)] = min(R(:,t));

NOTE — This is UNTESTED CODE but should work.

Best Answer

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MATLAB: Plot extreme values on a time series

MATLAB: In an assignment, number of elements in A and B must be same

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