How to plot frequency spectrum in log-log scale?

Hello,

I'm trying to plot a frequency spectrum for a given set of data with log scales in both axes which should scale as 10^0, 10^1,10^2........

I tried to write the code but its not generating the same.

Kindly let me know the corrections in the followint code. The data is as attached/uploaded herewith.

close all;
freq_sam = 100;                      % samples
period_ctrw = 0.005;                 % time period
freq_ctrw = 1/period_ctrw;            % frequency
data_ctrw = data.variable.turbulence(:,100);
x_data = data.variable.turbulence(:,1);
y_data = data.variable.turbulence(:,100);
disp(x_data);
disp(y_data);
signal_ctrw = data_ctrw;
fft_ctrw = fft(signal_ctrw);          % fourier transform
fft_ctrw = fftshift(fft_ctrw);        % performing fft shift
f = freq_sam/2*linspace(-1,1,freq_sam);
figure;
set(gca, 'YScale', 'log')
set(gca, 'XScale', 'log')
plot(f, fft_ctrw,'.','MarkerSize',24);

Answer 1

[Dyuman Joshi]

If you change the scale of axes and plot the data afterwards, the scale will get modified according to the data. Better to change the scale after plotting.

Note the warnings.

load('data5a_chi1-15.mat')

freq_sam = 100;                      % samples
period_ctrw = 0.005;                 % time period
freq_ctrw = 1/period_ctrw;            % frequency
data_ctrw = data.variable.turbulence(:,100);
x_data = data.variable.turbulence(:,1);
y_data = data.variable.turbulence(:,100);
%disp(x_data);
%disp(y_data);
signal_ctrw = data_ctrw;
fft_ctrw = fft(signal_ctrw);          % fourier transform
fft_ctrw = fftshift(fft_ctrw);        % performing fft shift
f = freq_sam/2*linspace(-1,1,freq_sam);
figure;
plot(f, fft_ctrw,'.','MarkerSize',24);

Warning: Imaginary parts of complex X and/or Y arguments ignored.

set(gca, 'XScale', 'log')
set(gca, 'YScale', 'log')

Warning: Negative data ignored

Answer 2

[Rahul]

Hi Dyuman Joshi,

Regarding the the above code for generating frequency spectrum, I'd like to know if it is possible to generate the profile which

looks like as attached? This type of profile is what I'm actually trying to generate. But not getting it. The data I'm using is attached herewith. Kindly let me know if possible.

Rgds