= release note : version guineapig++-0.5.4-b =

 
== Fast Fourier Transform : FFTW2 and FFTW3 ==

It is now possible tu use the very efficient fast Fourier Transform library FFTW, although the local fft is yet available. The distribution is foreseen for using the locally programmed fft, without any change.
It is better to use the FFTW. For that the user has to achieve following steps. 

 * make sure that at FFTW is installed on the site. This is available open source from : http://www.fftw.org). Know which version of fftw do you use : '''2.5.1''' or '''3.1.2'''.

 * update requirements files : 

       1. in the file <some root>/guineapig++/x.y.z-b/cmt/requirements, comment (with a '#') the line, so : 

{{{
#macro USE_FFT " USE_FFT_LOCAL "
}}} 

       2. uncomment, in the same requirements file the following lines, for '''fftw 2.5.1''' :

{{{
#for using fftw2 lib uncomment 2 following lines 
macro USE_FFT " USE_FFTW2 "
use CMT_FFTW v2*  $(guineapig++_root)/external/
}}}

for '''fftw 3.1.2''' :

{{{
#for using fftw3 lib uncomment 2 following lines
macro USE_FFT " USE_FFTW3 "
use CMT_FFTW v3*  $(guineapig++_root)/external/
}}}

       3. For '''fftw 2.5.1''' update in <some root>/guineapig++/x.y.z-b/external/CMT_FFTW/v2.5.1/cmt/requirements, the path for include (fftw.h) and library (libfftw.a) : 
{{{
   macro FFTW_INCLUDE  " /<your installation of fftw>/include "
   macro FFTW_LIB " /<your installation of fftw>/lib "
}}}
indicating the localization of your fftw. 
Or for '''fftw 3.1.2''' in <some root>/guineapig++/x.y.z-b/external/CMT_FFTW/v2.5.1/cmt/requirements, the path for include (fftw3.h) and library (libfftw.a) :

{{{
   macro FFTW_INCLUDE  " /<your installation of fftw3>/include "
   macro FFTW_LIB " /<your installation of fftw3>/lib "
}}}