how to save variable data that we changed ?

this is my code:

nSamp = 3251;
Fs = 1024e3;
SNR = 40;
rng default

t = (0:nSamp-1)'/Fs;

x = sin(2*pi*t*100.123e3);
x = x + randn(size(x))*std(x)/db2mag(SNR);

[Pxx,f] = periodogram(x,kaiser(nSamp,38),[],Fs);
meanfreq(Pxx,f);

i change the variable in this code to my dataset . then after run, the variable go to its original data . how to solve this problem?

[KSSV]

Which variable you have changed and how you have changed?

[NUR BATRISYIA HANNANI ZAIN AZMI]

variable for x . i insert my own value of data for x. but then after run with new data for variable , the variable data go back to its original value.

[Walter Roberson]

where do you insert the value? your line

x = sin(2*pi*t*100.123e3);

overwrites all of x

[NUR BATRISYIA HANNANI ZAIN AZMI]

i changed the value of x in workspace but then after run the coding , the value of x in workspace changed to old value . thus i get same graph generated with old value . so how should i do so that the value that i want in workspace can be saved and i can get the graph i want with new value of x?

i already overwrites all of x before.

[Walter Roberson]

We need to see your current code.

[Jorg Woehl]

Walter is right; you are defining x in your code, so what you have in the workspace doesn't matter. Without really knowing what you are trying to code, my guess would be that you need to remove at least this line:

x = sin(2*pi*t*100.123e3);

[NUR BATRISYIA HANNANI ZAIN AZMI]

ohh . so what code i need to write to define my own x? i want to find mean frequency for power spectral density .

[Walter Roberson]

What is the source of your signal? Is it stored in a .mat file at the moment? Does it need to be read from a .wav ?

[NUR BATRISYIA HANNANI ZAIN AZMI]

yes in mat file .

Answer 1

[TED MOSBY]

Hi @NUR BATRISYIA HANNANI ZAIN AZMI,

I understand that you want to change the value of a variable in the workspace. The problem you are facing is because you are changing the values in the workspace but that is not the right way as the variables in the workspace are generated after the script is executed.

So, changing the values in the workspace won’t help as when you run the script again it will generate the values according to the code and not take the values of the workspace.

So, to change any value of the variable you must modify the script. You can make your code as a function and then call it as shown below:

function plotPeriodogram(x) 
nSamp = numel(x); 
Fs = 1024e3; 
SNR = 40; 
rng default 
x = x + randn(size(x)) * std(x) / db2mag(SNR); 
[Pxx, f] = periodogram(x, kaiser(nSamp, 38), [], Fs); 
meanFreq = meanfreq(Pxx, f); 
disp(['Mean Frequency: ', num2str(meanFreq)]); 
end 
plotPeriodogram(myNewData); 

Hope this helps!