S 0 Index S 1 Introduction and General Information Q whatisfftw 1.1 What is FFTW? Q whereisfftw 1.2 How do I obtain FFTW? Q isfftwfree 1.3 Is FFTW free software? Q nonfree 1.4 What is this about non-free licenses? S 2 Installing FFTW Q systems 2.1 Which systems does FFTW run on? Q runOnDOS 2.2 Does FFTW run on DOS/Windows? Q compilerCrashes 2.3 My compiler has trouble with FFTW. Q solarisSucks 2.4 FFTW does not compile on Solaris, complaining about \courier{const\}. Q languages 2.5 Which language is FFTW written in? Q fortran 2.6 Can I call FFTW from FORTRAN? Q cplusplus 2.7 Can I call FFTW from C++? Q whynotfortran 2.8 Why isn't FFTW written in FORTRAN/C++? Q singleprec 2.9 How do I compile FFTW to run in single precision? S 3 Using FFTW Q slow 3.1 FFTW seems really slow. Q conventions 3.2 FFTW gives results different from my old FFT. Q savePlans 3.3 Can I save FFTW's plans? Q whyscaled 3.4 Why does your inverse transform return a scaled result? Q centerorigin 3.5 How can I make FFTW put the origin (zero frequency) at the center of its output? Q imageaudio 3.6 How do I FFT an image/audio file in \italic{foobar\} format? Q linkfails 3.7 My program does not link (on Unix). S 4 Internals of FFTW Q howworks 4.1 How does FFTW work? Q whyfast 4.2 Why is FFTW so fast? Q wisdom 4.3 What is this \courier{wisdom\} thing? Q whywisdom 4.4 Why do you use \courier{wisdom\}? I just wanted to save a plan. S 5 Known bugs Q rfftwndbug 5.1 FFTW 1.1 crashes in rfftwnd on Linux. Q fftwmpibug 5.2 The MPI transforms in FFTW 1.2 give incorrect results/leak memory. Q testsingbug 5.3 The test programs in FFTW 1.2.1 fail when I change FFTW to use single precision. Q teststoobig 5.4 The test program in FFTW 1.2.1 fails for n > 46340. Q linuxthreads 5.5 The threaded code fails on Linux Redhat 5.0 Q bigrfftwnd 5.6 FFTW 2.0's rfftwnd fails for rank > 1 transforms with a final dimension >= 65536. Q primebug 5.7 FFTW 2.0's complex transforms give the wrong results with prime factors 17 to 97. Q mpichbug 5.8 FFTW 2.1.1's MPI test programs crash with MPICH. Q aixthreadbug 5.9 FFTW 2.1.2's multi-threaded transforms don't work on AIX. Q bigprimebug 5.10 FFTW 2.1.2's complex transforms give incorrect results for large prime sizes.