FFTW, "The Fastest Fourier Transform in The West", is a C library which implements discrete Fourier Transforms. It is licensed under the GNU GPL.
FFTW homepage: http://www.fftw.org/
FAQ: http://www.fftw.org/faq/
Questions tagged [fftw]
883 questions
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Quaternion FFT using 1D FFT in C++
I am currently implemented research paper that use a Quaternion FFT in c++.
However, I could not find any C++ library that support Quaternion FFT.
After some surveys, I have found someone on the Internet said that it is possible to convert…
wlee
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FFT output is blank when using FFTW_MEASURE, but works fine with FFTW_ESTIMATE
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 fft convolution, so my example below includes both…
Harris M Snyder
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fatal error C1047 in release build only
My project uses Visual Studio 2012, and I am using the libfftw-3.3.lib as coming from their page.
When I build my project in debug, it links and compiles just fine, and I get a working application.
When I set it to release mode, the linker gives me…
SinisterMJ
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Using fftw with column major square matrices (armadillo library)
I find the armadillo C++ library very convenient for matrix computations. How does one perform a two dimensional FFT on armadillo matrices using the FFTW library?
I understand that armadillo matrix class stores data in a column major order. How do I…
userJ
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Why is cuFFT so slow?
I'm hoping to accelerate a computer vision application that computes many FFTs using FFTW and OpenMP on an Intel CPU. However, for a variety of FFT problem sizes, I've found that cuFFT is slower than FFTW with OpenMP.
In the experiments and…
solvingPuzzles
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FFTW: size of output array for 2D Fourier Transform of 3D data
I have a real 3D array of dimensions Nx*Ny*Nz and want to take a 2D Fourier transform for each z value using FFTW. Here the z index is the fastest varying in memory. Currently the following code works as expected:
int Nx = 16; int Ny = 8; int Nz =…
Hemmer
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FFTW - computing real 2D FFT, special requirements
I'm using FFTW3 to compute 2D real FFT in c++. I've read the manual but have some questions. From the manual: http://www.fftw.org/fftw3_doc/One_002dDimensional-DFTs-of-Real-Data.html#One_002dDimensional-DFTs-of-Real-Data
In exchange for these speed…
tir38
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Thread IDs with PPL and Parallel Memory Allocation
I have a question about the Microsoft PPL library, and parallel programming in general. I am using FFTW to perform a large set (100,000) of 64 x 64 x 64 FFTs and inverse FFTs. In my current implementation, I use a parallel for loop and allocate the…
Kyle Lynch
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Using FFTWLib (C#): Using fftw.dft_r2c_2d() crashes vshost.exe, or main program if vshost is not running
As the title states: I'm trying to use Tamas Szalay's C# port of FFTW in Visual C# 2010 Professional (Trial), and I'm getting the above error when I try to use a two-dimensional transform. (The problem persists when I switch to dft_c2r_2d()). Other…
linkhyrule5
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Solve Poisson's equation with FFTW, MPI and C programming language
Currently I am trying to implement a 3D solver for Poisson's equation thanks to the FFTW3 library and with MPI in C. My problem consists on solving the problem in Fourier space and then perform a backward transform which allows me to get the…
steven
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C++: Attemping to use std::rotate with fftw_complex data yields error: "array must be initialized with a brace-enclosed initializer"
I am trying to understand how to utilize the fft to process data I capture with a software defined radio. I discovered C++'s fftw3 library and attempted to look up some documentation or tutorials, and found there wasn't a whole ton to go off of.
I…
OzzlyOsborne
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FFTW single-precision library outputs incorrect DFT when using SIMD optimizations
I'm testing the FFTW 3.3.8 C library for 1D Discrete Fourier Transform (DFT) calculations. The results I get are often incorrect when I use the float (single-precision) version of the libraries, configured with the --enable-generic-simd128 or…
Puk
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Compare FFT speed of python (scipy and pyfftw packages) and matlab
I compared the speed of FFT using different methods in python and matlab, the results looked a little weird and I didn't know if I did it right. The code in python are as follows:
from scipy import fft
import pyfftw
import numpy as np
from timeit…
shz
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FFTW results differ from FFT in MATLAB
I compare the forward FFT using FFTW and MATLAB fft. The input signal is a Gaussian. Code:
FFTW using C:
float *signal; /*input signal*/
int nt; /*length of the signal*/
fftw_complex *in, *out;
fftw_plan plan1;
in =…
clduan
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Two Dimensional FFTW Help
I'm currently trying to compute the fft of an image via fftw_plan_dft_2d.
To use this function, I'm linearizing the image data into an in array and calling the function mentioned above (and detailed below)
ftw_plan fftw_plan_dft_2d(int n0, int n1,
…
djs22
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