INSTALL

Installing the software
***********************

Hardware requirements
=====================

SkyMaker runs in (ANSI) text-mode from a shell. A window system is not
necessary.

When it comes to memory usage, the amount required by SkyMaker depends on the
size of the image being generated (about 8 times the number of pixels).

Note that SkyMaker takes advantage of multiple CPU cores for most operations.


Obtaining SkyMaker
===============

For Linux users, the simplest way to have SkyMaker up and running is
to install the standard binary package the comes with your Linux
distribution. Run, e.g., "apt-get SkyMaker" (on Debian) or "dnf install SkyMaker"
(Fedora) and SkyMaker, as well as all its dependencies, will
automatically be installed. If you decided to install the package this
way you may skip the following and move straight to the next section.

However if SkyMaker is not available in your distribution, or to
obtain the most recent version, the SkyMaker source package can be
downloaded from the official GitHub repository. One may choose one of
the stable releases, or for the fearless, a copy of the current master
development branch.


Software requirements
=====================

SkyMaker has been developed on GNU/Linux machines and should compile
on any POSIX-compliant system (this includes Apple OS X and Cygwin
on Microsoft Windows, at the price of some difficulties with the
configuration), provided that the development package of the
following library has been installed:

* FFTw V3.0 and above [2],

On Fedora/Redhat distributions for instance, the development package
above is available as "fftw-devel". FFTw is not required if SkyMaker is linked
with Intel's MKL (Math Kernel Library) library.


Installation
============

To install from the GitHub source package, you must first uncompress
the archive:

   $ unzip SkyMaker-<version>.zip

A new directory called "skymaker-<version>" should now appear at the
current location on your disk. Enter the directory and generate the
files required by the autotools, which the package relies on:

   $ cd skymaker-<version>
   $ sh autogen.sh

A "configure" script is created. This script has many options, which
may be listed with the "--help" option:

   $ ./configure --help

No options are required for compiling with the default GNU C compiler
("gcc") if all the required libraries are installed at their default
locations:

   $ ./configure

Compared to "gcc" and the librairies above, the combination of the
Intel compiler ("icc") and the MKL (Math Kernel Library) libraries
can give the SkyMaker executable a significant boost in performance,
thanks to better vectorized code, and reduced memory usage. If "icc"
and the MKL (Math Kernel Library) are installed on your system [3],
you can take advantage of those using instead

   $ ./configure --enable-mkl

Additionally, if the SkyMaker binary is to be run on a different
machine that does not have "icc" and the MKL (Math Kernel Library)
installed (e.g., a cluster computing node), you must configure a
partially statically linked executable using

   $ ./configure --enable-mkl --enable-auto-flags --enable-best-link

In all cases, SkyMaker can now be compiled with

   $ make -j

An "src/skymaker" executable is created. For system-wide installation,
run the usual

   $ sudo make install

You may now check that the software is properly installed by simply
typing in your shell:

   $ sky

(note that some shells require the "rehash" command to be run before
making a freshly installed executable accessible in the execution
path).

[1] Mac OS X ".dmg" packages should be available soon.

[2] Make sure that FFTw has been compiled with "configure"
    options "--enable-threads --enable-float".

[3] The Linux versions of the Intel compiler and MKL (Math
    Kernel Library) are available for free to academic researchers,
    students, educators and open source contributors.