Installation

Download from www.tu-chemnitz.de/$\sim$ potts/nfft the most recent version nfft3.x.x.tgz. In the following, we assume that you use a bash compatible shell. Uncompress the archive.

• tar xfvz nfft3.x.x.tar.gz

Change to the newly created directory.

• cd nfft3.x.x

Optional: Set environment variables (see also below). Leave this step out, if you are unsure what to do. Example:

• export CFLAGS="$(CFLAGS) -O3 -D GAUSSIAN -I/path/to/include/files"
  (If you run a csh, this reads as setenv CFLAGS "..."; if $(CFLAGS) is not defined, use export CFLAGS="-O3 -D GAUSSIAN ...")
• export LDFLAGS="$(LDFLAGS) -L/path/to/libraries"

Run the configure script.

• ./configure

Compile the sources.

• make

This builds the NFFT library and all examples and applications. You can run make install to install the library on your system. If for example /usr is your default installation directory, make install will copy the NFFT 3 library to /usr/lib, the C header files to /usr/include/nfft and the documentation together with all examples and applications to /usr/share/nfft.

For more information on fine grained control over the installation directories, run the configure script with the option --help, i.e. ./configure --help. For example, to see what gets installed, run ./configure --prefix=some/path/to/a/temporary/directory in the line of commands above. After make and make install, you will find all installed files in the directory structure created under the temporary directory.

The following options are determined at compile time. The NFFT routines use the Kaiser-Bessel window function (KAISER_BESSEL) by default. You can change the used window function by setting the environment variable CFLAGS accordingly prior to running the configure script. For example, to use the Gaussian window function, set CFLAGS to include -D GAUSSIAN.

• export CFLAGS="$(CFLAGS) -D GAUSSIAN"

Analogously, you can set NFFT to use the Sinc window function (SINC_POWER) or the B-spline window function (B_SPLINE).

The NFFT transforms can be configured to measure elapsed time for each step of Algorithm 1 and 2. This option should help to customise the library to one's needs. One can enable this option by defining MEASURE_TIME and/or MEASURE_TIME_FFTW in CFLAGS.

• export CFLAGS="$(CFLAGS) -D MEASURE_TIME -D MEASURE_TIME_FFTW"