fftw Questions

3

Solved

I am compiling a test program to test the fftw3 (ver3.3.4). Since it is not installed with root previlidge the command I used is: gcc -lm -L/home/my_name/opt/fftw-3.3.4/lib/ -I/home/my_name/opt/ff...
Cown asked 29/8, 2014 at 12:10

2

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I have C++ code which uses FFTW 3.3.4. Ubuntu 16.04, cmake version 3.7.2 $ locate *fftw*.so /usr/lib/libsfftw.so /usr/lib/libsfftw_mpi.so /usr/lib/libsfftw_threads.so /usr/lib/libsrfftw.so /usr/l...
Hatchment asked 31/5, 2017 at 6:21

1

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I am trying to solve the 1D heat equation using a complex to complex IDFT. The problem is that the output after a single timestep does not seem to be correct. I have included a simple example below...
Anglosaxon asked 1/10, 2020 at 12:29

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I am trying to FFT an image using the library from http://www.fftw.org/ so that I can do a convolution in the frequency domain. But I can't figure out how to make it work. To understand how to do t...
Paperback asked 17/10, 2011 at 7:59

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Can I expect a speedup when using FFTW (http://www.fftw.org/) instead of OpenCV's cvDFT (http://goo.gl/YCHj0)? My program's runtime is heavily determined by the application of inverse and forward ...
Thoria asked 3/5, 2012 at 17:45

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I wish to call fftw's in-place real-to-complex transform function, which has the following signature: fftw_plan fftw_plan_dft_r2c_1d( int n, // transform length double* in, // pointer to input a...
Etheline asked 1/9, 2019 at 21:42

1

I have a program that I am trying to run in the Visual Studio Code debugger that uses fftw functions. It compiles with the command g++ dimer.cpp -std=c++11 -lfftw3 on the terminal on my computer ...
Corot asked 23/7, 2019 at 22:42

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I'm trying to visualize a signal and its frequency spectrum in Julia. I found the FFTW package that provides the FFT and DSP for the frequencies. Here is what I'm trying, with a sinusoidal signal...
Spirillum asked 7/5, 2019 at 20:59

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I have been fighting with a very weird bug for almost a month. Asking you guys is my last hope. I wrote a program in C that integrates the 2d Cahn–Hilliard equation using the Implicit Euler (IE) sc...
Tyre asked 28/11, 2018 at 11:30

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I am trying to write a FORTRAN code to evaluate the fast Fourier transform of the Gaussian function f(r)=exp(-(r^2)) using FFTW3 library. As everyone knows, the Fourier transform of the Gaussian fu...
Showery asked 23/11, 2018 at 2:17

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I am learning how to handle the FFTW package with fortran. To produce an easily verifiable example, I compute the power spectrum of a 2d plane, which I fill with two distinct superpositioned waves....
Larder asked 6/6, 2018 at 17:41

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I am trying to use Eigen unsupported FFT library using FFTW backend. Specifically I am want to do a 2D FFT. Here's my code : void fft2(Eigen::MatrixXf * matIn,Eigen::MatrixXcf * matOut) { const i...
Gawlas asked 5/4, 2018 at 16:5

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I have written a C program that uses FFTW to compute derivative (repeatedly) of a function. I am testing for simple sin(x) function. Each step computes the derivative of the answer of the previous ...
Manuelmanuela asked 25/1, 2018 at 21:22

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I'm using Windows 10 and Visual Studio 2015. In C++, I need to get the Fourier-transform of an image for applying filters on it. It seems that FFTW++ is the ideal solution for this, however I can't...
Inflatable asked 24/9, 2016 at 10:41

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I take blocks of incoming data and pass them through fftw to get some spectral information. Everything seems to be working, however I think I'm getting some aliasing issues. I've been trying to wo...
Sevenfold asked 24/8, 2010 at 9:59

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I'm trying to find the oscillation and spectrum frequency of the waveform generated by a vector of data representing the motion of a pixel in an image. The data is stored in a .txt file, as follow...
Succor asked 25/4, 2017 at 14:57

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I am trying to run FFTW code in a mex file. This is strictly for the purpose of development and testing. After some googling, I see that others have tried to do something similar and have had relat...
Paralyze asked 24/3, 2011 at 15:44

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Suppose that I have a sequence x(n) which is K * N long and that only the first N elements are different from zero. I'm assuming that N << K, say, for example, N = 10 and K = 100000. I want t...
Digastric asked 16/11, 2016 at 15:46

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I am trying to compute the FFT and then the IFFT just to try out if I can get the same signal back but I am not really sure how to accomplish it. This is how I do the FFT: plan = fftw_plan_r2r_1d...
Consistence asked 16/4, 2011 at 10:2

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I'm compiling octave on my LFS - Linux from scratch - system. While configuring octave, I receive a warning: configure: WARNING: FFTW3F library not found. The slower FFTPACK library will be used i...
Hallucinate asked 17/5, 2016 at 4:55

2

I want to analyze a signal I get from my microphone port by using portaudio and fftwpp. For that I followed the explanation provided here. My questions concerning that are now: There it is stated t...
Aguascalientes asked 29/2, 2016 at 13:55

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I'm having the following issue in my attempt to use fftw3. For some reason, whenever I do an FFT using FFTW_MEASURE instead of FFTW_ESTIMATE, I get blank output. Ultimately I'm trying to implement ...
Hangdog asked 11/12, 2015 at 17:55

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Edit: I resolved this issue, the solution is below. I am building a code in a shared computing cluster dedicated for scientific computing, thus I can only control files in my home folder. Although...
Form asked 4/11, 2015 at 10:37

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I have a matrix stored in row-major order. I am trying to compute the DCT of a ub-matrix using FFTW, and I get nonsense. In the following paragraphs I will describe the problem and my solution, and...
Schoolboy asked 30/7, 2015 at 9:18

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What is the fastest FFT implementation in Python? It seems numpy.fft and scipy.fftpack both are based on fftpack, and not FFTW. Is fftpack as fast as FFTW? What about using multithreaded FFT, or u...
Yolanthe asked 15/6, 2011 at 23:28

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