<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"> <html> <head><title> FFTW FAQ - Section 2 </title> <link rev="made" href="mailto:fftw@fftw.org"> <link rel="Contents" href="index.html"> <link rel="Start" href="index.html"> <link rel="Next" href="section3.html"><link rel="Previous" href="section1.html"><link rel="Bookmark" title="FFTW FAQ" href="index.html"> </head><body text="#000000" bgcolor="#FFFFFF"><h1> FFTW FAQ - Section 2 <br> Installing FFTW </h1> <ul> <li><a href="#systems" rel=subdocument>Q2.1. Which systems does FFTW run on?</a> <li><a href="#runOnDOS" rel=subdocument>Q2.2. Does FFTW run on DOS/Windows?</a> <li><a href="#compilerCrashes" rel=subdocument>Q2.3. My compiler has trouble with FFTW.</a> <li><a href="#solarisSucks" rel=subdocument>Q2.4. FFTW does not compile on Solaris, complaining about <code>const</code>.</a> <li><a href="#languages" rel=subdocument>Q2.5. Which language is FFTW written in?</a> <li><a href="#fortran" rel=subdocument>Q2.6. Can I call FFTW from FORTRAN?</a> <li><a href="#cplusplus" rel=subdocument>Q2.7. Can I call FFTW from C++?</a> <li><a href="#whynotfortran" rel=subdocument>Q2.8. Why isn't FFTW written in FORTRAN/C++?</a> <li><a href="#singleprec" rel=subdocument>Q2.9. How do I compile FFTW to run in single precision?</a> </ul><hr> <h2><A name="systems"> Question 2.1. Which systems does FFTW run on? </A></h2> FFTW is written in ANSI C, and should work on any system with a decent C compiler. (See also <A href="#runOnDOS">Q2.2 `Does FFTW run on DOS/Windows?'</A> and <A href="#compilerCrashes">Q2.3 `My compiler has trouble with FFTW.'</A>.) <h2><A name="runOnDOS"> Question 2.2. Does FFTW run on DOS/Windows? </A></h2> It should. FFTW was not developed on DOS or Windows, but the source code is straight ANSI C. Some users have reported using FFTW on DOS/Windows using various compilers. See also the <A href="http://www.fftw.org/install/install-Windows.html">FFTW Windows installation notes</A> and <A href="#compilerCrashes">Q2.3 `My compiler has trouble with FFTW.'</A> <h2><A name="compilerCrashes"> Question 2.3. My compiler has trouble with FFTW. </A></h2> Complain fiercely to the vendor of the compiler. <p> FFTW is a heavily-optimized piece of software that is likely to push compilers to their limits. We had no problems with, for example, <code>gcc 2.7.2</code>, <code>egcs 1.1.x</code>, Sun's <code>SC4.0</code>, and IBM's <code>XLC</code>. Users have also reported successful compilations of FFTW using Borland's C/C++ compilers on Windows. <p> Visual C++ 4.0 crashes when compiling FFTW 1.2 with all optimizations turned on. Visual C++ 5.0 reportedly produces incorrect code for the real transforms in FFTW 2.x when the option "Maximize speed" is set. We are told that Service Pack 3 fixes the bug. <p> Metrowerks CodeWarrior Pro 4 reportedly generates incorrect code for the PowerPC when compiling FFTW at optimization level 4. Supposedly, this bug is fixed in CW Pro 5 with all the latest updates applied. (No problems were reported for previous versions.) <p> Various problems have also been observed with SGI's MIPSpro compilers, versions 7.2.0 and 7.2.1 (you may have to lower the optimization level for some files to get them to compile); the bug seems to be fixed in version 7.3. The test program in earlier versions of FFTW had problems with the <code>-xO5</code> option in Sun's <code>SC4.0</code> C compiler. <code>egcs 1.0.2</code> produced incorrect code for FFTW on the PowerPC (corrected in <code>egcs 1.1</code>). <h2><A name="solarisSucks"> Question 2.4. FFTW does not compile on Solaris, complaining about <code>const</code>. </A></h2> We know that at least on Solaris 2.5.x with Sun's compilers 4.2 you might get error messages from <code>make</code> such as <p> <code>"./fftw.h", line 88: warning: const is a keyword in ANSI C</code> <p> This is the case when the <code>configure</code> script reports that <code>const</code> does not work: <p> <code>checking for working const... (cached) no</code> <p> You should be aware that Solaris comes with two compilers, namely, <code>/opt/SUNWspro/SC4.2/bin/cc</code> and <code>/usr/ucb/cc</code>. The latter compiler is non-ANSI. Indeed, it is a perverse shell script that calls the real compiler in non-ANSI mode. In order to compile FFTW, change your path so that the right <code>cc</code> is used. <p> To know whether your compiler is the right one, type <code>cc -V</code>. If the compiler prints ``<code>ucbcc</code>'', as in <p> <code>ucbcc: WorkShop Compilers 4.2 30 Oct 1996 C 4.2</code> <p> then the compiler is wrong. The right message is something like <p> <code>cc: WorkShop Compilers 4.2 30 Oct 1996 C 4.2</code> <h2><A name="languages"> Question 2.5. Which language is FFTW written in? </A></h2> FFTW is written in ANSI C. Most of the code, however, was automatically generated by a program called <code>genfft</code>, written in the Objective Caml dialect of ML. You do not need to know ML or to have an Objective Caml compiler in order to use FFTW. <p> <code>genfft</code> is provided with the FFTW sources, which means that you can play with the code generator if you want. In this case, you need a working Objective Caml system. Objective Caml is available from <code>ftp.inria.fr</code> in the directory <A href="ftp://ftp.inria.fr/lang/caml-light"><code>/lang/caml-light</code></A>. <h2><A name="fortran"> Question 2.6. Can I call FFTW from FORTRAN? </A></h2> Yes, but not directly. The main problem is that Fortran cannot pass parameters by value. However, FFTW can be called indirectly from Fortran through the use of special C "wrapper" routines. Appropriate wrapper code, documented in the FFTW manual, is included with FFTW (versions 1.3 and higher). <h2><A name="cplusplus"> Question 2.7. Can I call FFTW from C++? </A></h2> Most definitely. FFTW should compile and run under any C++ compiler. <h2><A name="whynotfortran"> Question 2.8. Why isn't FFTW written in FORTRAN/C++? </A></h2> Because we don't like those languages, and neither approaches the portability of C. <h2><A name="singleprec"> Question 2.9. How do I compile FFTW to run in single precision? </A></h2> On a Unix system: <code>configure --enable-float</code>. On a non-Unix system: edit <code>fftw/fftw.h</code> to <code>#define</code> the symbol <code>FFTW_ENABLE_FLOAT</code>. In both cases, you must then recompile FFTW. <hr> Next: <a href="section3.html" rel=precedes>Using FFTW</a>.<br> Back: <a href="section1.html" rev=precedes>Introduction and General Information</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> - 07 November 1999 </address><br> Extracted from FFTW Frequently Asked Questions with Answers, Copyright © 1999 Massachusetts Institute of Technology. </body></html>
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