const.
FFTW is a heavily-optimized piece of software that is likely to push
compilers to their limits. We had no problems with, for example,
gcc 2.7.2, egcs 1.1.x, Sun's SC4.0, and IBM's XLC. Users have also reported successful compilations of FFTW using Borland's C/C++ compilers on Windows.
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.
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.)
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 -xO5 option in Sun's SC4.0 C compiler. egcs 1.0.2 produced incorrect code for FFTW on the PowerPC (corrected in egcs 1.1).
const.
make such as
"./fftw.h", line 88: warning: const is a keyword in ANSI
C
This is the case when the configure script reports that const does not work:
checking for working const... (cached) no
You should be aware that Solaris comes with two compilers, namely,
/opt/SUNWspro/SC4.2/bin/cc and /usr/ucb/cc. 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
cc is used.
To know whether your compiler is the right one, type
cc -V. If the compiler prints ``ucbcc'', as in
ucbcc: WorkShop Compilers 4.2 30 Oct 1996 C
4.2
then the compiler is wrong. The right message is something like
cc: WorkShop Compilers 4.2 30 Oct 1996 C
4.2
genfft, 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.
genfft 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 ftp.inria.fr in the directory /lang/caml-light.
configure --enable-float. On a non-Unix system: edit fftw/fftw.h to #define the symbol FFTW_ENABLE_FLOAT. In both cases, you must then recompile
FFTW. Matteo Frigo and Steven G. Johnson / fftw@fftw.org - 07 November 1999