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
, Sun's SC4.0
, IBM's XLC
, Metrowerks' compilers for the Macintosh, and SGI's compilers for IRIX
6.2. 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.
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 test program in earlier
versions of FFTW had problems with the -xO5
option in Sun's SC4.0
C compiler.
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@theory.lcs.mit.edu - 30 March 1999