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<!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/leakmemory.</a><li><a href="#testsingbug" rel=subdocument>Q5.3. The test programs in FFTW 1.2.1 fail when I change FFTW to use singleprecision.</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 finaldimension >= 65536.</a><li><a href="#primebug" rel=subdocument>Q5.7. FFTW 2.0's complex transforms give the wrong results with primefactors 17 to 97.</a><li><a href="#mpichbug" rel=subdocument>Q5.8. FFTW 2.1.1's MPI test programs crash withMPICH.</a><li><a href="#aixthreadbug" rel=subdocument>Q5.9. FFTW 2.1.2's multi-threaded transforms don't work onAIX.</a><li><a href="#bigprimebug" rel=subdocument>Q5.10. FFTW 2.1.2's complex transforms give incorrect results for large primesizes.</a><li><a href="#aixflags" rel=subdocument>Q5.11. FFTW 2.1.3 crashes on AIX</a></ul><hr><h2><A name="rfftwndbug">Question 5.1. FFTW 1.1 crashes in rfftwnd onLinux.</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 showedup 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 incorrectresults/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 causeerrors in some situations. <h2><A name="testsingbug">Question 5.3. The test programs in FFTW 1.2.1 fail when I change FFTWto use single precision.</A></h2>This bug was fixed in FFTW 1.3. (Older versions of FFTW didwork in single precision, but the test programs didn't--the errortolerances 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 naivetransform that we used for comparison overflows 32 bit integerprecision, breaking the test. <h2><A name="linuxthreads">Question 5.5. The threaded code fails on Linux Redhat5.0</A></h2>We had problems with glibc-2.0.5. The code should work withglibc-2.0.7. <h2><A name="bigrfftwnd">Question 5.6. FFTW 2.0's rfftwnd fails for rank > 1 transformswith a final dimension >= 65536.</A></h2>This bug was fixed in FFTW 2.0.1. (There was a 32-bit integeroverflow due to a poorly-parenthesized expression.) <h2><A name="primebug">Question 5.7. FFTW 2.0's complex transforms give the wrong resultswith prime factors 17 to 97.</A></h2>There was a bug in the complex transforms that could cause incorrectresults under (hopefully rare) circumstances for lengths withintermediate-size prime factors (17-97). This bug was fixed in FFTW2.1.1. <h2><A name="mpichbug">Question 5.8. FFTW 2.1.1's MPI test programs crash withMPICH.</A></h2>This bug was fixed in FFTW 2.1.2. The 2.1/2.1.1 MPI test programscrashed 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 onAIX.</A></h2>This bug was fixed in FFTW 2.1.3. The multi-threaded transforms inprevious 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 resultsfor large prime sizes.</A></h2>This bug was fixed in FFTW 2.1.3. FFTW's complex-transform algorithmfor prime sizes (in versions 2.0 to 2.1.2) had an integer overflowproblem that caused incorrect results for many primes greater than32768 (on 32-bit machines). (Sizes without large prime factors arenot affected.) <h2><A name="aixflags">Question 5.11. 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. Thisis 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>- 24 March 2003</address><br>Extracted from FFTW Frequently Asked Questions with Answers,Copyright © 2003 Massachusetts Institute of Technology.</body></html>⌨️ 快捷键说明
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