fftw

问题 I need to use FFTW with different arithmetic precisions and multithreaded plans. I need to setup multithreading for all precisions? Like this: fftwf_init_threads(); fftwf_plan_with_nthreads(nthreads); fftw_init_threads(); fftw_plan_with_nthreads(nthreads); fftwl_init_threads(); fftwl_plan_with_nthreads(nthreads); Or writing this in my start routine fftw_init_threads(); fftw_plan_with_nthreads(nthreads); will be enough? 回答1: The fftw libraries for different precisions are completely

问题 I am having trouble explaining/understanding the following phenomenon: To test fftw3 i am using the 2d poisson test case: laplacian(f(x,y)) = - g(x,y) with periodic boundary conditions. After applying the fourier transform to the equation we obtain : F(kx,ky) = G(kx,ky) /(kx² + ky²) (1) if i take g(x,y) = sin (x) + sin(y) , (x,y) \in [0,2 \pi] i have immediately f(x,y) = g(x,y) which is what i am trying to obtain with the fft : i compute G from g with a forward Fourier transform From this i

问题 I am trying to use the FFTW3 guru interface. However, the description in the documentation causes me more confusion that clarity. I want to create a plan for 3 scalar complex FFTs, each of length n , which should be aligned in memory one after the other (interleaved arrays). I do not understand whether this implies rank == 3 or howmany_rank == 3 . I also don't know, which values the arrays fftw_iodim *dims and const fftw_iodim *howmany_dims need to have. While this stackexchange post seems to

问题 Heading Hi, I'm trying to multiply two arrays of fftw_complex types, how should i do it? Here's the code: fftw_complex *rInF, *gInF, *bInF; fftw_complex *rOutF, *gOutF, *bOutF; for(int i=0;i<m_image->width()*m_image->height();i++) { //realis rInF[i][0] = rIn[i][0]*rInMask[i][0] - rIn[i][1]*rInMask[i][1]; gInF[i][0] = gIn[i][0]*gInMask[i][0] - gIn[i][1]*gInMask[i][1]; bInF[i][0] = bIn[i][0]*bInMask[i][0] - bIn[i][1]*bInMask[i][1]; //imaginalis rInF[i][1] = rIn[i][1]*rInMask[i][0] + rIn[i][0]

问题 I have a pretty involving program that uses an in house FFT algorithm. I recently decided to try using FFTW for a performance increase. Just as a simple test to ensure that FFTW would link and run, I added the following code to the beginning of the application, however, when I run, I get a segmentation fault when I create the fftwf_plan : const size_t size = 1024; vector<complex<float> > data(size); for(size_t i = 0; i < size; ++i) data[i] = complex<float>(i, -i); fftwf_plan plan = fftwf_plan

问题 Hi I am getting below error while compiling a c code using gcc /usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../lib64/crt1.o: In function `_start': (.text+0x20): undefined reference to `main' collect2: ld returned 1 exit status I am trying to import the fftw() function into SystemVerilog. Here is my code #include <stdio.h> #include <stdlib.h> #include <stdint.h> #include <math.h> #include <fftw3.h> void fftw(double FFT_in[],int size) { double *IFFT_out; int i; fftw_complex *middle; fftw

问题 I'm trying to install fftw-2.1.5 libraries on a IBM cluster with linux, with the --enable-mpi flag, but I have since failed to do so. I need fftw version 2.1.5 because GADGET2 code requires that version, with mpi support. First, I installed mpich-3.0.4 with: cd ~/mpich-3.0.4 ./configure --prefix=$HOME --enable-shared make make install Then I edited my .bashrc file, adding: export LD_LIBRARY_PATH="$HOME/lib" PATH=$PATH:$HOME/bin Then I tried to install ffw: ./configure --prefix=$HOME/test -

问题 I am writing a program to help people learn guitar. To do this, I need to be able to look at a sample of time and see what note(s) they played. I looked at FFTW but I don't understand how to get this to work. I also tried to figure out the Goertzel algorithm but it seems like that is just for single-frequency notes like dial tones (not sure about that though). To be clear, I do need to be able to detect multiple notes (to see if a chord is played), but it doesn't matter too much if a few

问题 I've written a piece of C code that uses libfftw3 and libaiff external libraries. The code compiles and executes perfectly on my machine which has the required libraries and is running OS X 10.9 Mavericks. I'm using Xcode 5.1 to compile my program and I believe I have linked the required libraries correctly and provided the necessary paths to header files etc. (Everything works as it should on my computer). In fact, the resulting executable also runs on another computer running OS X Mavericks

问题 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 that I should chunk a window out of the incoming data. My data is already chunked, after I am only recording for a short time, and afterwards process it. Thus I am assuming that a rectangular window is already applied to my data. Is that correct? Now I am getting 200k data points, should I directly