fftw

问题 I want to plot the frequency spectrum (like they do for example in Audacity). Hence I want the frequency in Hertz on the x-axis and the amplitude on the y-axis. My input is a periodically sine wave with 0,7 as amplitude and 500HZ as frequency.I use FFTW to compute the magnitude and QWT to plot. My problem , what parameters should I put in setSamples to get a pic on 500 HZ ? Any help would be appreciated here is my code 回答1: From documentation you must set two pointers to data that build the

问题 I'm using Ubuntu 12 64 bit, installed fftw library version 2.1.5. I have a c++ project with use CMake to build the make file. This is my cmakelist.text: project(MP) cmake_minimum_required(VERSION 2.8) if(TYPE STREQUAL "Debug") set(CMAKE_BUILD_TYPE "Debug") else() set(CMAKE_BUILD_TYPE "Release") endif() if(CMAKE_COMPILER_IS_GNUCXX) add_definitions( -std=c++11 ) endif() find_package(GLUT REQUIRED) find_package(OpenGL REQUIRED) find_library(GLUI libglui.a ./vendor/lib) include_directories($

问题 I'm using Ubuntu 12 64 bit, installed fftw library version 2.1.5. I have a c++ project with use CMake to build the make file. This is my cmakelist.text: project(MP) cmake_minimum_required(VERSION 2.8) if(TYPE STREQUAL "Debug") set(CMAKE_BUILD_TYPE "Debug") else() set(CMAKE_BUILD_TYPE "Release") endif() if(CMAKE_COMPILER_IS_GNUCXX) add_definitions( -std=c++11 ) endif() find_package(GLUT REQUIRED) find_package(OpenGL REQUIRED) find_library(GLUI libglui.a ./vendor/lib) include_directories($

问题 I am interested in computing the fft of the first rows of a matrix, but I do not know in advance how many rows I need. I need to do this repeatedly but the number of rows I need to transform can change. I will illustrate with the following example. Suppose I have a 100 by 128 array. If I plan for 1-dimensional fft's on each row, FFTW produces the following plan: (dft-ct-dit/8 (dftw-direct-8/28-x100 "t2fv_8_sse2") (dft-vrank>=1-x8/1 (dft-direct-16-x100 "n1fv_16_sse2"))) Although I don't fully

问题 I'm trying to use Visual Studio 2015 to compile a project that uses FFTW. Unfortunately, the precompiled binaries from the FFTW website aren't compatible with VS 2015, due to this problem: unresolved external symbol __imp__fprintf and __imp____iob_func, SDL2. You get a link error when you try to compile. I'm looking for any advice on how I can compile a compatible version. The obvious answer would be to recompile FFTW with VS 2015, but I can't find any instructions on how to compile it with

问题 I am trying fftw with c++. I want to test that it works correct. I implemented a simple ifft(fft(shift(data)) - data == 0 test, that fails completely. The testdata is a rect function, with amplitude and phase 1. The matlab code for comparison works perfectly with the same test. The basic question is: what am I doing wrong? Here the matlab code (which is also using fftw...) FFTW dll/.h is latest. data = zeros(1, 64); halfsize = numel(data)/2; data(halfsize-10:halfsize+10) = 1; phase = ones

问题 Nowdays I just want to use FFTW3 on iOS, since I've compiled it successfully into i386 version which is used by the iOS simulator, the rest work is to compile it into armv6(or v7) version and lipo these two versions together,below is my incorrect configure: ./configure CC=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/arm-apple-darwin10-gcc-4.2.1 LD=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/ld CCFLAGS="-I /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4

问题 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 DFT and I am thinking about using FFTW instead of OpenCV cvDFT. IIRC FFTW does some kind of "runtime compilation" whereas cvDFT is a simple FFT implementation, so I guess it could speed up my processing a bit. So before I am trying it out by myself, I thought to ask in here in case anyone stumbled

问题 Blow is a main file PROGRAM SPHEROID USE nrtype USE SUB_INFO INCLUDE "/usr/local/include/fftw3.f" INTEGER(I8B) :: plan_forward, plan_backward INTEGER(I4B) :: i, t, int_N REAL(DP) :: cth_i, sth_i, real_i, perturbation REAL(DP) :: PolarEffect, dummy, x1, x2, x3 REAL(DP), DIMENSION(4096) :: dummy1, dummy2, gam, th, ph REAL(DP), DIMENSION(4096) :: k1, k2, k3, k4, l1, l2, l3, l4, f_in COMPLEX(DPC), DIMENSION(2049) :: output1, output2, f_out CHARACTER(1024) :: baseOutputFilename CHARACTER(1024) ::

问题 I'm trying to link third party libraries like fftw3 and sndfile to my iPhone project in Xcode3.2. I got it working in a regular Mac project by setting the "Header Search Path" to "/usr/local/include" and the "Other Linker Flags" to "-lfftw3 -lsndfile" under the project build configuration. However, it gave me "library not found for -lfftw3" with exit code 1 error message when I tried to build it in the iPhone project using the same settings. Does apple not allow this on the iPhone? Is there a