fftw

How to use FFTW DLL import library .lib as a static .lib in my project?

由 牧云@^-^@ 提交于 2020-07-21 07:38:48
问题 I've knowledge of C++ and compiling small plug-ins (always based on a similar and laid out workflow). Though currently I need to compile the latest version of FFTW into a static library (or get it from the compiled version which should supposedly be a lot easier) and it's giving me an insanely hard time. Probably because I don't know the ins and outs of compiling. As a note I'm working on Windows with Visual Studio. Since I really want to know how this should work I'm asking the question here

matlab中fft快速傅里叶变换

由 萝らか妹 提交于 2020-04-24 22:50:28
视频来源： https://www.bilibili.com/video/av51932171?t=628 。 博文来源：https://ww2.mathworks.cn/help/matlab/ref/fft.html?searchHighlight=fft&s_tid=doc_srchtitle 视频来源很好的解释了： 1 .傅里叶变换过程，经过傅里叶变化得到了，频率w，振幅a0，相位角φ； 2. 傅里叶变换 主要应用领域： 声音， 图像处理； 博文则很好的解释了： 1. 傅里叶变换在matlab软件中怎样应用 2.. 傅里叶变换的作用效果的展示，从时域到频域的变化，时域难以解决的问题到频域中却很清晰。 语法 Y = fft(X) Y = fft(X,n) Y = fft(X,n,dim) 说明 示例 Y = fft( X ) 用快速傅里叶变换 ( FFT) 算法计算 X 的 离散傅里叶变换 (DFT)。 如果 X 是向量，则 fft(X) 返回该向量的傅里叶变换。 如果 X 是矩阵，则 fft(X) 将 X 的各列视为向量，并返回每列的傅里叶变换。 如果 X 是一个多维数组，则 fft(X) 将沿大小不等于 1 的第一个数组维度的值视为向量，并返回每个向量的傅里叶变换。 示例 Y = fft( X , n ) 返回 n 点 DFT。如果未指定任何值，则 Y 的大小与 X 相同

AudioRecord : How can I use a common buffer to use it for processing and storing?

由 半世苍凉 提交于 2020-01-13 17:08:54
问题 I have an AudioRecord thread that writes to database. Now I want to use some audio data in buffer at some intervals and process it using FFT . I want to send audio buffer to FFT as parameter. When I am trying to use a common buffer then its giving me libc error. How can I use a common buffer to pass it to FFT and also write it to a storage? When I tried using different read calls there was situation of data loss and hence cant use that. Following is my code public void start() {

Matlab's fftn gets slower with multithreading?

由 ≯℡__Kan透↙ 提交于 2020-01-13 13:50:10
问题 I have access to a 12 core machine and some matlab code that relies heavily on fftn. I would like to speed up my code. Since the fft can be parallelized I would think that more cores would help but I'm seeing the opposite. Here's an example: X = peaks(1028); ncores = feature('numcores'); ntrials = 20; mtx_power_times = zeros(ncores,ntrials); fft_times = zeros(ncores, ntrials); for i=1:ncores for j=1:ntrials maxNumCompThreads(i); tic; X^2; mtx_power_times(i,j) = toc; tic fftn(X); fft_times(i,j

scaling factor for CUFFT

由 对着背影说爱祢 提交于 2020-01-11 05:12:14
问题 I wrote a simple test program, where I was doing Complex to Complex FT's and I just generated some data 1..50 and stuck it in for the real and imaginary part for each index of the array. When I do an operation like this IFFT(FFT(A)) = A to test them out, I am getting different results for each library. FFTW, I have to divide the output by len(A) to get back the original A However, doing this forward then reverse FFT with CUFFT, it looks like I have to divide by (sqrt(2)*50) to get back to the

How do I use fftw_plan_many_dft on a transposed array of data?

由 ￡可爱￡侵袭症＋ 提交于 2020-01-09 19:51:21
问题 I have a 2D array of data stored in column-major (Fortran-style) format, and I'd like to take the FFT of each row . I would like to avoid transposing the array (it is not square). For example, my array fftw_complex* data = new fftw_complex[21*256]; contains entries [r0_val0, r1_val0,..., r20_val0, r0_val1,...,r20_val255] . I can use fftw_plan_many_dft to make a plan to solve each of the 21 FFTs in-place in the data array if it is row -major, e.g. [r0_val0, r0_val1,..., r0_val255, r1_val0,...

Real-time impulse response convolution with FFTW — result sounds like IR is symmetrical

由 回眸只為那壹抹淺笑 提交于 2020-01-06 20:01:58
问题 For research purposes I am building a real-time reverb convolution engine in C++ using FFTW (and PortAudio for the sound delivery) with the overlap-add method for convolution. Most of it is working, but a very peculiar effect occurs. Though I can't see why, it sounds very much as if the impulse response becomes symmetrical: what was h[n] becomes h[n] + h[-n] . Does anyone know if performing FFT in the way I describe below would have this effect? Basically, my process is as follows: Known in

fftw split example crashes

由 China☆狼群 提交于 2020-01-06 16:08:03
问题 I'm trying to use fftw (3.3.4) on split arrays. I took an example from a C/MEX guide ( PDF : http://www.researchgate.net/publictopics.PublicPostFileLoader.html?id=551a2e59cf57d7620c8b463b&key=3a91499f-ec8f-41f4-8e87-fff8bf00e54a). When the program is run it crashes (segfault). Running valgrind shows memory violations. What am I doing wrong here? #include <vector> #include <fftw3.h> void DivideArray(double *Data, int NumEl, double Divisor) { int n; for(n = 0; n < NumEl; n++) Data[n] /= Divisor

fftw split example crashes

由 若如初见. 提交于 2020-01-06 16:07:25
问题 I'm trying to use fftw (3.3.4) on split arrays. I took an example from a C/MEX guide ( PDF : http://www.researchgate.net/publictopics.PublicPostFileLoader.html?id=551a2e59cf57d7620c8b463b&key=3a91499f-ec8f-41f4-8e87-fff8bf00e54a). When the program is run it crashes (segfault). Running valgrind shows memory violations. What am I doing wrong here? #include <vector> #include <fftw3.h> void DivideArray(double *Data, int NumEl, double Divisor) { int n; for(n = 0; n < NumEl; n++) Data[n] /= Divisor

fftw split example crashes

由 旧时模样 提交于 2020-01-06 16:06:26
问题 I'm trying to use fftw (3.3.4) on split arrays. I took an example from a C/MEX guide ( PDF : http://www.researchgate.net/publictopics.PublicPostFileLoader.html?id=551a2e59cf57d7620c8b463b&key=3a91499f-ec8f-41f4-8e87-fff8bf00e54a). When the program is run it crashes (segfault). Running valgrind shows memory violations. What am I doing wrong here? #include <vector> #include <fftw3.h> void DivideArray(double *Data, int NumEl, double Divisor) { int n; for(n = 0; n < NumEl; n++) Data[n] /= Divisor
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