Re: fft support on octave

[Kai Torben Ohlhus]

On 12/14/19 1:24 AM, niraj pandey wrote:
> On Fri, Dec 13, 2019 at 4:45 PM niraj pandey <address@hidden
> <mailto:address@hidden>> wrote:
> 
> 
> 
>     On Fri, Dec 13, 2019 at 2:22 PM Kai Torben Ohlhus
>     <address@hidden <mailto:address@hidden>> wrote:
> 
>         On 12/13/19 5:39 PM, niraj pandey wrote:> On Fri, Dec 13, 2019
>         at 1:19
>         PM Kai Torben Ohlhus <address@hidden <mailto:address@hidden>
>         > <mailto:address@hidden <mailto:address@hidden>>> wrote:
>         >
>         >
>         >
>         >     On 12/13/19 3:48 PM, niraj pandey wrote:
>         >     > On Fri, Dec 13, 2019 at 12:14 PM Kai Torben Ohlhus
>         >     <address@hidden <mailto:address@hidden>
>         <mailto:address@hidden <mailto:address@hidden>>>
>         >     >> On 12/13/19 3:14 PM, niraj pandey wrote:
>         >     >>> Hi ,
>         >     >>>
>         >     >>> Could you pls help me how to build octave with fft
>         support. I
>         >     used the
>         >     >>> following command to build octave but still getting issue.
>         >     >>>
>         >     >>>
>         >     >>> octave:1> fft(0:255)
>         >     >>> error: fft: support for FFTW was unavailable or
>         disabled when
>         >     liboctave
>         >     >>> was built
>         >     >>>
>         >     >>>
>         >     >>> ./configure --prefix=/home/niraj/oc CFLAGS=-fPIC
>         CXXFLAGS=-fPIC
>         >     >>> --enable-shared --with-gui --with-qt
>         >     >>> --with-blas=/v5.1.0/BLAS-3.8.0/blas_LINUX.a
>         >     >>> --with-lapack=/v5.1.0/lapack-3.8.0/liblapack.a
>         --enable-float
>         >     >>> --enable-sse --with-fftw3-includedir=/tmp/fftw/include/
>         >     >>> --with-fftw3-libdir=/tmp/fftw/lib
>         >     >>>
>         >     >>> Config.log says:   configure:69014: WARNING: FFTW3
>         library not
>         >     found.
>         >     >>> The slower FFTPACK library will be used instead.
>         >     >>>
>         >     >>> Thanks
>         >     >>> Niraj
>         >     >>
>         >     >> Dear Niraj,
>         >     >>
>         >     >> Still I do not understand why you deploy libraries in
>         the "/tmp"
>         >     >> directory, which is on usual Linux system a volatile
>         TeMPorary
>         >     >> directory.  Can't you use your user's /home/niraj
>         directory for all
>         >     >> libraries instead?  This might be one root of trouble.
>         >     >>
>         >     >> Can you describe, how you installed the FFTW3 library
>         on your system?
>         >     >>
>         >     >> HTH,
>         >     >> Kai
>         >     >>
>         >     >
>         >     > Hello Kai,
>         >     >
>         >     > I used the following command to install FFTW3.
>         >     >
>         >     > ./configure --prefix=/home/niraj/fftw --enable-float
>         --enable-sse
>         >     >
>         >     > To install the tool on /tmp area first is just check all the
>         >     > dependencies required by that tool . Once I identify all the
>         >     > dependencies I install the tool on production area
>         through some
>         >     > automated process :)
>         >     >
>         >     > Thanks
>         >     > Niraj
>         >
>         >     Can you submit a small portion of config.log around the error
>         >
>         >     >>> configure:69014: WARNING: FFTW3 library not found.
>         >
>         >     Usually there is a program which is compiled during
>         ./configure and this
>         >     normally contains the compiler output which might be
>         helpful to get to
>         >     the root of the trouble.
>         >
>         >     Best,
>         >     Kai
>         >
>         >
>         > Hi Kai,
>         >
>         > PFA config.log files for fftw and octave .
>         >
>         > Thanks
>         > Niraj
>         >
> 
> 
>         Please always answer below the text.  The interesting portion is
>         this:
> 
>         $ ./configure --prefix=/home/niraj/oc CFLAGS=-fPIC CXXFLAGS=-fPIC
>         --enable-shared --with-gui --with-qt
>         --with-blas=common/pkgs/octave/v5.1.0/BLAS-3.8.0/blas_LINUX.a
>         --with-lapack=common/pkgs/octave/v5.1.0/lapack-3.8.0/liblapack.a
>         --enable-float --enable-sse
>         --with-fftw3-includedir=/tmp/fftw/include/
>         --with-fftw3-libdir=/tmp/fftw/lib
> 
>         configure:68911: $? = 1
>         configure:68936: checking fftw3.h usability
>         configure:68936: gcc -std=gnu11 -c -fPIC -pthread -fopenmp
>         -I/tmp/fftw/include/  conftest.c >&5
>         configure:68936: $? = 0
>         configure:68936: result: yes
>         configure:68936: checking fftw3.h presence
>         configure:68936: gcc -std=gnu11 -E -I/tmp/fftw/include/  conftest.c
>         configure:68936: $? = 0
>         configure:68936: result: yes
>         configure:68936: checking for fftw3.h
>         configure:68936: result: yes
>         configure:68947: checking for fftw_plan_dft_1d in -lfftw3
>         configure:68978: gcc -std=gnu11 -o conftest -fPIC -pthread -fopenmp
>         -I/tmp/fftw/include/  -L/tmp/fftw/lib -L/tmp/fftw/lib
>         -Wl,-rpath=/tmp/fftw/lib conftest.c -lfftw3  -lm  >&5
>         /usr/bin/ld: cannot find -lfftw3
>         collect2: error: ld returned 1 exit status
>         configure:68978: $? = 1
> 
>         Is there in `/tmp/fftw/lib` some `libfftw3.so` or is it in
>         `/tmp/fftw/lib64`?
> 
>         HTH,
>         Kai
> 
> 
> 
>     I do not see any libfftw3.so library there. Instead of that I found
>     "libfftw3f.so" under lib.
> 
>     Thanks
>     Niraj
>
>
> Sharing logs zip file here.
>
> Thanks
> Niraj
>


When reading the configure script of fftw

   ./configure --help
       [...]
       --enable-shared[=PKGS]  build shared libraries [default=no]
       [...]
       --enable-single         compile fftw in single precision
       --enable-float          synonym for --enable-single
       --enable-long-double    compile fftw in long-double precision
       [...]

you should change your configure flags to:

   ./configure --prefix=/tmp/fftw --enable-shared \
      --enable-float --enable-long-double --enable-sse

HTH,
Kai