how to do spectrum analyse with FFTW? - Stack Overflow
https://stackoverflow.com/questions/23879566/how-t ...
You can find more details in FFTW's documentation. However, for the relatively simple case of one-dimensional real-valued signal, the following is a sum-up of the general steps you have to do. Typically you would need to ...
FFTW signal spectrum - Stack Overflow
https://stackoverflow.com/questions/43209070/fftw- ...
Here are the few things that aren't quite right: In the time-domain plot, 100 points at a sampling rate of 1000Hz should give you a total duration of 0.1 second. The formula used for signalX is correct assuming that timePassed is ...
Computing a 3D power spectrum in fftw - Stack Overflow
https://stackoverflow.com/questions/36729067/compu ...
It's simpler than you think: the vector (i, j, k) is already the wave vector, so you get the associated frequency by taking its length and dividing it by the length of the edge of your cube. f = sqrt(i*i + j*j + k*k)/edgelength. The result is the spacial ...
How to plot spectrum using FFTW3/ QWT? - Stack Overflow
https://stackoverflow.com/questions/24353795/how-t ...
From documentation you must set two pointers to data that build the curve and the size (number of samples in your case). void QwtPlotCurve::setSamples(const double *xData, const double *yData, int size). In your case yData ...
Tutorial - FFTW
http://www.fftw.org/fftw2_doc/fftw_2.html
This chapter describes the basic usage of FFTW, i.e., how to compute the Fourier transform of a single array. ... As an example, here is an outline of how you might use RFFTW to compute the power spectrum of a real array (i.e. the squares of ...