MATLAB Answers

Plotting FRF with imaginary and real numbers

21 views (last 30 days)
Ana Bianco
Ana Bianco on 19 Aug 2019
Commented: Ana Bianco on 16 Sep 2019
Hello, I have a file of all the FRF functions of an experiment, and it is computed in complex numbers + real part. I would like to know if it is possible to plot the graphic of it (resulting in the natural frequencies and stuff) only having this data?
it is like this:
-0.0915237963199616 + 0.00000000000000i -0.0666214004158974 - 0.0629538968205452i -0.0647708997130394 - 0.0962110981345177i 0.000384484999813139 - 0.189506992697716i 0.104717001318932 - 0.171706005930901i 0.145686000585556 - 0.117163002490997i 0.148408994078636 - 0.0817890018224716i 0.150115996599197 - 0.0637563988566399i 0.149434000253677 - 0.0457847006618977i 0.151601999998093 - 0.0343611985445023i 0.144703000783920 - 0.0156481992453337i 0.134606003761292 - 0.00748514989390969i 0.119563996791840 - 0.00314980000257492i and so on

  0 Comments

Sign in to comment.

Accepted Answer

Star Strider
Star Strider on 19 Aug 2019
I would like to know if it is possible to plot the graphic of it (resulting in the natural frequencies and stuff) only having this data?
It is.
However you also need to have the associated frequency vector if you want to make any sense of it.

  7 Comments

Show 4 older comments
Ana Bianco
Ana Bianco on 14 Sep 2019
Another thing... the results I have were generated from 0 to 8000 hz, and the FRF's (imaginary and real part) were generated for each 0,625 hz, so we got here 12800. But instead of plotting a graphic for each 12800 point, i want to make the frequency sample for each 10 hz, "smoothing" the function. Is it possible? How can I write down this frequency vector?
Star Strider
Star Strider on 14 Sep 2019
I actually have no idea, because none of those numbers were in your original question.
Try this:
FRF = [ -0.0915237963199616 + 0.00000000000000i; -0.0666214004158974 - 0.0629538968205452i; -0.0647708997130394 - 0.0962110981345177i; 0.000384484999813139 - 0.189506992697716i; 0.104717001318932 - 0.171706005930901i; 0.145686000585556 - 0.117163002490997i; 0.148408994078636 - 0.0817890018224716i; 0.150115996599197 - 0.0637563988566399i; 0.149434000253677 - 0.0457847006618977i; 0.151601999998093 - 0.0343611985445023i; 0.144703000783920 - 0.0156481992453337i; 0.134606003761292 - 0.00748514989390969i; 0.119563996791840 - 0.00314980000257492i];
Fv = linspace(0, 1, numel(FRF))*8000; % Frequency Vector
figure
plot(Fv, abs(FRF))
grid
xlabel('Frequency')
ylabel('Amplitude')
Fvi = linspace(0, 1, max(Fv)/10)*max(Fv); % New Frequency Vector
FRFi = interp1(Fv, abs(FRF), Fvi, 'pchip'); % Interpolate
figure
plot(Fvi, FRFi)
grid
xlabel('Frequency')
ylabel('Amplitude')
Experiment to get the result you want.
Ana Bianco
Ana Bianco on 16 Sep 2019
Sorry about it, but ok, I'll try it! Thanks!

Sign in to comment.

More Answers (0)

Sign in to answer this question.