Mercurial > hg > sv-dependency-builds
diff src/fftw-3.3.5/doc/FAQ/fftw-faq.html/section5.html @ 127:7867fa7e1b6b
Current fftw source
| author | Chris Cannam <cannam@all-day-breakfast.com> |
|---|---|
| date | Tue, 18 Oct 2016 13:40:26 +0100 |
| parents | |
| children |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/fftw-3.3.5/doc/FAQ/fftw-faq.html/section5.html Tue Oct 18 13:40:26 2016 +0100 @@ -0,0 +1,148 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"> +<html> +<head><title> +FFTW FAQ - Section 5 +</title> +<link rev="made" href="mailto:fftw@fftw.org"> +<link rel="Contents" href="index.html"> +<link rel="Start" href="index.html"> +<link rel="Previous" href="section4.html"><link rel="Bookmark" title="FFTW FAQ" href="index.html"> +</head><body text="#000000" bgcolor="#FFFFFF"><h1> +FFTW FAQ - Section 5 <br> +Known bugs +</h1> + +<ul> +<li><a href="#rfftwndbug" rel=subdocument>Q5.1. FFTW 1.1 crashes in rfftwnd on Linux.</a> +<li><a href="#fftwmpibug" rel=subdocument>Q5.2. The MPI transforms in FFTW 1.2 give incorrect results/leak +memory.</a> +<li><a href="#testsingbug" rel=subdocument>Q5.3. The test programs in FFTW 1.2.1 fail when I change FFTW to use single +precision.</a> +<li><a href="#teststoobig" rel=subdocument>Q5.4. The test program in FFTW 1.2.1 fails for n > +46340.</a> +<li><a href="#linuxthreads" rel=subdocument>Q5.5. The threaded code fails on Linux Redhat 5.0</a> +<li><a href="#bigrfftwnd" rel=subdocument>Q5.6. FFTW 2.0's rfftwnd fails for rank > 1 transforms with a final +dimension >= 65536.</a> +<li><a href="#primebug" rel=subdocument>Q5.7. FFTW 2.0's complex transforms give the wrong results with prime +factors 17 to 97.</a> +<li><a href="#mpichbug" rel=subdocument>Q5.8. FFTW 2.1.1's MPI test programs crash with +MPICH.</a> +<li><a href="#aixthreadbug" rel=subdocument>Q5.9. FFTW 2.1.2's multi-threaded transforms don't work on +AIX.</a> +<li><a href="#bigprimebug" rel=subdocument>Q5.10. FFTW 2.1.2's complex transforms give incorrect results for large prime +sizes.</a> +<li><a href="#solaristhreadbug" rel=subdocument>Q5.11. FFTW 2.1.3's multi-threaded transforms don't give any speedup on +Solaris.</a> +<li><a href="#aixflags" rel=subdocument>Q5.12. FFTW 2.1.3 crashes on AIX.</a> +</ul><hr> + +<h2><A name="rfftwndbug"> +Question 5.1. FFTW 1.1 crashes in rfftwnd on +Linux. +</A></h2> + +This bug was fixed in FFTW 1.2. There was a bug in +<code>rfftwnd</code> causing an incorrect amount of memory to be allocated. The bug showed +up in Linux with libc-5.3.12 (and nowhere else that we know of). + +<h2><A name="fftwmpibug"> +Question 5.2. The MPI transforms in FFTW 1.2 give incorrect +results/leak memory. +</A></h2> + +These bugs were corrected in FFTW 1.2.1. The MPI transforms (really, +just the transpose routines) in FFTW 1.2 had bugs that could cause +errors in some situations. +<h2><A name="testsingbug"> +Question 5.3. The test programs in FFTW 1.2.1 fail when I change FFTW +to use single precision. +</A></h2> + +This bug was fixed in FFTW 1.3. (Older versions of FFTW did +work in single precision, but the test programs didn't--the error +tolerances in the tests were set for double precision.) + +<h2><A name="teststoobig"> +Question 5.4. The test program in FFTW 1.2.1 fails for n > +46340. +</A></h2> + +This bug was fixed in FFTW 1.3. FFTW 1.2.1 produced the right answer, +but the test program was wrong. For large n, n*n in the naive +transform that we used for comparison overflows 32 bit integer +precision, breaking the test. +<h2><A name="linuxthreads"> +Question 5.5. The threaded code fails on Linux Redhat +5.0 +</A></h2> + +We had problems with glibc-2.0.5. The code should work with +glibc-2.0.7. +<h2><A name="bigrfftwnd"> +Question 5.6. FFTW 2.0's rfftwnd fails for rank > 1 transforms +with a final dimension >= 65536. +</A></h2> + +This bug was fixed in FFTW 2.0.1. (There was a 32-bit integer +overflow due to a poorly-parenthesized expression.) +<h2><A name="primebug"> +Question 5.7. FFTW 2.0's complex transforms give the wrong results +with prime factors 17 to 97. +</A></h2> + +There was a bug in the complex transforms that could cause incorrect +results under (hopefully rare) circumstances for lengths with +intermediate-size prime factors (17-97). This bug was fixed in FFTW +2.1.1. +<h2><A name="mpichbug"> +Question 5.8. FFTW 2.1.1's MPI test programs crash with +MPICH. +</A></h2> + +This bug was fixed in FFTW 2.1.2. The 2.1/2.1.1 MPI test programs +crashed when using the MPICH implementation of MPI with the +<code>ch_p4</code> device (TCP/IP); the transforms themselves worked fine. + +<h2><A name="aixthreadbug"> +Question 5.9. FFTW 2.1.2's multi-threaded transforms don't work on +AIX. +</A></h2> + +This bug was fixed in FFTW 2.1.3. The multi-threaded transforms in +previous versions didn't work with AIX's +<code>pthreads</code> implementation, which idiosyncratically creates threads in detached +(non-joinable) mode by default. +<h2><A name="bigprimebug"> +Question 5.10. FFTW 2.1.2's complex transforms give incorrect results +for large prime sizes. +</A></h2> + +This bug was fixed in FFTW 2.1.3. FFTW's complex-transform algorithm +for prime sizes (in versions 2.0 to 2.1.2) had an integer overflow +problem that caused incorrect results for many primes greater than +32768 (on 32-bit machines). (Sizes without large prime factors are +not affected.) +<h2><A name="solaristhreadbug"> +Question 5.11. FFTW 2.1.3's multi-threaded transforms don't give any +speedup on Solaris. +</A></h2> + +This bug was fixed in FFTW 2.1.4. (By default, Solaris creates +threads that do not parallelize over multiple processors, so one has +to request the proper behavior specifically.) + +<h2><A name="aixflags"> +Question 5.12. FFTW 2.1.3 crashes on AIX. +</A></h2> + +The FFTW 2.1.3 <code>configure</code> script picked incorrect compiler flags for the <code>xlc</code> compiler on newer IBM processors. This +is fixed in FFTW 2.1.4. <hr> +Back: <a href="section4.html" rev=precedes>Internals of FFTW</a>.<br> +<a href="index.html" rev=subdocument>Return to contents</a>.<p> +<address> +<A href="http://www.fftw.org">Matteo Frigo and Steven G. Johnson</A> / <A href="mailto:fftw@fftw.org">fftw@fftw.org</A> +- 30 July 2016 +</address><br> +Extracted from FFTW Frequently Asked Questions with Answers, +Copyright © 2016 Matteo Frigo and Massachusetts Institute of Technology. +</body></html>