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Questions tagged [continuous-fourier]

Use this tag for questions about computation of exact continuous-time Fourier transform (e.g. using symbolic software like Sage, Mathematica, Sympy). For the discrete Fourier transform and fast Fourier transform, use tag [fft].

63 questions
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nonlinear Schroedinger equation resolution with split step method

I'm trying to resolve a nonlinear PDE Schrödinger equation with the split-step Fourier pseudo-spectral method. The fonction "solver" is supposed to solve the time and space dependant equation with the split-step method but it gives values…
rbalint99
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Matlab - Symbolic computation for a Fourier transform : no result

In Matlab, I would like to compute the inverse Fourier transform symbolically of the following function : cf=1/(1 - beta*t*1i)^N But impossible to get a result with : >> ifourier(cf,t,x) ans = fourier(1/(1 - beta*t*1i)^N, t, -x)/(2*pi) Isn't…
user1773603
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Numpy FFT function results are not correct to transform time domain to frequency domain data

I have a problem with the results obtained from running sets of codes of numpy FFT functions in my python 3.7. The problem is that the frequency vs amplitude and frequency vs Power spectrum density plots are not correct - judging from the shape and…
Muhammad Hisham
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Converting wav to mp3 from python

I'm not sure the best way to ask this question, but here goes. I created my own way to do a type of Fourier transform, and I would like to see if this gives me better compression than the standard methods of FFT. Currently, I am reading in a wav…
lee
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Inverse of fourier transform in 3d for non-uniform grid

My data is given by the Fourier transform of the function, where the points are distributed in a ball with uniformly distributed distances and uniformly distributed spherical angles (not Gaussian angles). So the grid in Fourier space is obviously…
Fedor Goncharov
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Comparing analytic vs numeric Fourier Transform of `exp(-mod(x))`

I'd like to understand the difference between an analytic and numeric FT of a function, using the numpy.fft module (i.e. why they are not the same). Starting with the equation , the Fourier Transform of this can be shown to give an analytical FT…
markmuetz
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Can any function be decomposed as sum of Gaussians?

In Fourier series, any function can be decomposed as sum of sine and cosine In neural networks, any function can be decomposed as weighted sum over logistic functions. (A one layer neural network) In wavelet transforms, any function can be…
Rob Romijnders
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how to find Fourier coefficients in matlab?

i have vin which is the input voltage of circuit . (=taw) vin[(-taw/4)-->(taw/4)]=0.75 vin[(taw/4)-->(3*taw/4)]=-0.25 and the voltage is repeated,this is a square input voltage. () = ∑ cos (2t/) now i need to find Fourier coefficients: ak= 2/*∫ ()…
kayan
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FFT Gauss VS Fourier Transform (by hand) Gauss

In a Fortran program I am using the Fourier Transform of a given function the user can choose. But the user already has to write the Fourier transform of the function. So I wanted to extend the program in a way the user only have to give the…
MorganeMaPh
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Taking fourier transform of a function using symbolic variable

MATLAB failed to compute the fft of this function: syms t; x= 1/(1+t^2); X= fft(x) And threw this error: Undefined function 'fft' for input arguments of type 'sym'. Why didn't it take the Fourier transform of the symbolic variable? I think it…
Uygar Uçar
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How to draw a Fourier spectra for my txt file data on MatLab?

I have a ground-based magnetic data in txt file taken every second and I want to plot its Fourier Spectra. And I notice the spectrogram equation on MatLab need this parameters (window, noverlap, nfft, Fs) which I don't know. And I notice also that I…
Aliaa Abdelnasser
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Calculate the fourier transformation in python

I have a (theoretical) algorithm I want to implement in python. In this algorithm I have a start function called f, and I have to apply the fourier transformation and the inverse fourier transformation several times on this function. Is there a way…
arc_lupus
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Real-life application of sinc-in-time data or sinc(t) function?

I found that my customers' response time on an application is varying in a Sinc-in-time fashion. i.e. Sinc(t) across time. Can this information be applied to obtain any relevant system other than just for a fun observation?
lejin
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On Fourier Transform: how to resolve TypeError: Cannot convert complex to float

I am trying to compute for the Fourier Transform but keep on getting TypeError: Cannot convert complex to float. def x(t, k): return np.exp(-k * t**2) * sy.sin(k*t) * t**4 def get_x_FT(x, f, k): x_FT_integrand_real = lambda t: np.real(x(t,…
dvv
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scipy Fast fourier transform doesn't recognize the signal

i'm trying to get the frequency of a signal via fourier transform but it's not able to recognize it (sets the peak to f=0). Maybe something is wrong in my code (FULL reprudible code at the end of the page): PF = fft.fft(Y[0,:])/Npoints #/Npoints to…
Pancio
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