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FFTW FREQUENTLY ASKED QUESTIONS WITH ANSWERS
27 Jul 2006
Matteo Frigo
Steven G. Johnson
<fftw@fftw.org>
This is the list of Frequently Asked Questions about FFTW, a collection of
fast C routines for computing the Discrete Fourier Transform in one or
more dimensions.
Index
Section 1- Introduction and General Information
- Section 2
- Installing FFTW
- Section 3
- Using FFTW
- Section 4
- Internals of FFTW
- Section 5
- Known bugs
Section 1, Introduction and General Information
- Question 1.1
- What is FFTW?
- Question 1.2
- How do I obtain FFTW?
- Question 1.3
- Is FFTW free software?
- Question 1.4
- What is this about non-free licenses?
- Question 1.5
- In the West? I thought MIT was in the East?
Section 2, Installing FFTW
- Question 2.1
- Which systems does FFTW run on?
- Question 2.2
- Does FFTW run on Windows?
- Question 2.3
- My compiler has trouble with FFTW.
- Question 2.4
- FFTW does not compile on Solaris, complaining about
const.
- Question 2.5
- What's the difference between --enable-3dnow and
--enable-k7?
- Question 2.6
- What's the difference between the fma and the non-fma
versions?
- Question 2.7
- Which language is FFTW written in?
- Question 2.8
- Can I call FFTW from Fortran?
- Question 2.9
- Can I call FFTW from C++?
- Question 2.10
- Why isn't FFTW written in Fortran/C++?
- Question 2.11
- How do I compile FFTW to run in single precision?
- Question 2.12
- --enable-k7 does not work on x86-64
Section 3, Using FFTW
- Question 3.1
- Why not support the FFTW 2 interface in FFTW 3?
- Question 3.2
- Why do FFTW 3 plans encapsulate the input/output
arrays and not just the algorithm?
- Question 3.3
- FFTW seems really slow.
- Question 3.4
- FFTW slows down after repeated calls.
- Question 3.5
- An FFTW routine is crashing when I call it.
- Question 3.6
- My Fortran program crashes when calling FFTW.
- Question 3.7
- FFTW gives results different from my old FFT.
- Question 3.8
- Can I save FFTW's plans?
- Question 3.9
- Why does your inverse transform return a scaled
result?
- Question 3.10
- How can I make FFTW put the origin (zero frequency) at
the center of its output?
- Question 3.11
- How do I FFT an image/audio file in *foobar* format?
- Question 3.12
- My program does not link (on Unix).
- Question 3.13
- I included your header, but linking still fails.
- Question 3.14
- My program crashes, complaining about stack space.
- Question 3.15
- FFTW seems to have a memory leak.
- Question 3.16
- The output of FFTW's transform is all zeros.
- Question 3.17
- How do I call FFTW from the Microsoft language du
jour?
- Question 3.18
- Can I compute only a subset of the DFT outputs?
Section 4, Internals of FFTW
- Question 4.1
- How does FFTW work?
- Question 4.2
- Why is FFTW so fast?
Section 5, Known bugs
- Question 5.1
- FFTW 1.1 crashes in rfftwnd on Linux.
- Question 5.2
- The MPI transforms in FFTW 1.2 give incorrect
results/leak memory.
- Question 5.3
- The test programs in FFTW 1.2.1 fail when I change
FFTW to use single precision.
- Question 5.4
- The test program in FFTW 1.2.1 fails for n > 46340.
- Question 5.5
- The threaded code fails on Linux Redhat 5.0
- Question 5.6
- FFTW 2.0's rfftwnd fails for rank > 1 transforms with
a final dimension >= 65536.
- Question 5.7
- FFTW 2.0's complex transforms give the wrong results
with prime factors 17 to 97.
- Question 5.8
- FFTW 2.1.1's MPI test programs crash with MPICH.
- Question 5.9
- FFTW 2.1.2's multi-threaded transforms don't work on
AIX.
- Question 5.10
- FFTW 2.1.2's complex transforms give incorrect results
for large prime sizes.
- Question 5.11
- FFTW 2.1.3's multi-threaded transforms don't give any
speedup on Solaris.
- Question 5.12
- FFTW 2.1.3 crashes on AIX.
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