For loop overwrites values in signal

Hi,

I have vibration signal measured on rotating machinery consiting of 1D values (length 13000). I have 50 wav files, which I have now processed and stored in one termed x - each column in x is a serperate wave file measuring the machinery at a different time (so x is 50 columns).

I would like to rapidly process each of the wave files stored in x and store the output in to several .mat files representing each analysis. An example of what I want I am trying to acheive is below. I manage to get the loop through each 50 columns, but on each occasion it overwrites the ouput file. Please can anyone advise on how I can individually analyse each column and save.

Any help is appreciated, thanks alot.

for ii= 1:50
    max=max(x(:,ii); % ideally this would save the max of x all in one file called 'max', each column corresponding to the max of each wav file stored in x.
    rms=rms(x(:,ii)); % ideally this would save the rms of x all in one file called 'rms', each column corresponding to the rms of each wav file stored in x.
    % and further analysis can be performed here.
end

Answer 1

[Star Strider]

First, please do not use ‘max’ as a variable name. It is the name of the max function (obviously) and variable names take precedence over function names in MATLAB. This is called ‘overshadowing’ a MATLAB function name, and is to be avoided. (I am surprised that your code actually works beyond the first iteration because of that.)

Second, subscript the results:

maxv = zeros(1,50)
rmsv = zeros(1,50);
for ii= 1:50
    maxv(ii) = max(x(:,ii); % ideally this would save the max of x all in one file called 'max', each column corresponding to the max of each wav file stored in x.
    rmsv(ii) = rms(x(:,ii)); % ideally this would save the rms of x all in one file called 'rms', each column corresponding to the rms of each wav file stored in x.
    % and further analysis can be performed here.
end

That should work, and give you correct results.

Since MATLAB uses column-major evaluations,.you might be able to do that entirely without the loop:

maxv = max(x);
rmsv = rms(x);

[Ben]

Thanks, that worked!

[Star Strider]

As always, my pleasure!