How to make calculations over an interval throughout an entire vector?

I have a vector, say "Voltage" and it's 400 elements long. I want to calculate the min and max every 100 indicies and store that in a vector. How can I do that? I was thinking a for loop would be what I want, but I don't know how to make the loop scan the entire Voltage vector and make the min and max calculations every 100 indicies. Would it be a nested loop?

Answer 1

[Star Strider]

I would use the movmax function and its friends, or if you want to calculate the maximum or minimum over 100-element blocks of your vector, use the reshape function. Note that reshape requires that your vector be an integer multiple of 100 elements, or that you truncate it to meet that criterion.

[Anonymous]

But I want to calculate other things besides min and max. Those are just two of the things I need. Then what would you suggest? Also, if the vector isn't an event multiple of 100, for my index in the for loop how can I make it go every 100 until the end of Voltage?

I know it's something along the lines of 100:100:end(Voltage) but the end(Voltage) is where I'm stuck and don't know what to put.

[Star Strider]

I was thinking of something like this:

V = randi(9, 25, 1)                                 % Column Vector
N = 10;                                             % Segment Length
Vm = reshape(V(1:N*fix(numel(V)/N)), N, [])         % Truncate Vector & Create Matrix

Then take the max, min, or whatever metrics you want over each column of the resulting matrix.

If your vector is a row vector, you can convert it to a column vector with:

YourColVector = YourRow Vector(:); 

then use my code with your vector and without alteration, other than assigning 100 to ‘N’.

Experiment to get the result you want.

[Anonymous]

I would like to convert this into a loop though because i need more calculations done. How would I make this into a loop?

[Star Strider]

This is much more efficient than than a loop.

What calculations do you need to do?

[Anonymous]

finding the mean over the same invtervals throughout the vector

[Star Strider]

Take the mean of the matrix my code creates. It will automatically take the mean of the columns.