= Frequently Asked Questions (FAQ) =
[[TracNav(Help/FAQ/toc)]]


== General #general

=== Can I use PALM for my research? Is it free?
Yes, PALM is free software. It can be redistributed and/or modified under the terms of the GNU General Public License (v3).

=== Do I need to cite PALM in publications?
You are free to use PALM as permitted under the terms and conditions of the license. We kindly request that you cite PALM in your publications and presentations. We suggest the following citation as appropriate:

First description of the model:\\
'''Raasch, S. and M. Schröter (2001)''': PALM - a large-eddy simulation model performing on massively parallel computers. Meteorol. Z. 10, 363–372'''

Most recent description:\\
'''Maronga, B., Gryschka, M., Heinze, R., Hoffmann, F., Kanani-Sühring, F., Keck, M., Ketelsen, K., Letzel, M. O., Sühring, M., and Raasch, S. (2015)''': The Parallelized Large-Eddy Simulation Model (PALM) version 4.0 for atmospheric and oceanic flows: model formulation, recent developments, and future perspectives, Geosci. Model Dev., 8, 1539-1637, DOI:10.5194/gmd-8-2515-2015


=== Can I get a copy of the PALM logo?
Until PALM revision r2717, the logo came shipped with PALM. Since r2718, the logo can be downloaded [download:20 here].

== Installation #installation

=== Can I use any Fortran compiler to install PALM?
PALM can be compiled with recent versions of all major Fortran compilers. Frequently used compilers by the developers team are Intel, Cray, PGI and GNU. Please make sure you are always using a recent version. We can not guarantee compatibility of the PALM code with outdated compiler versions.

=== Are there any known issues with specific Fortran compiler versions?
Yes, PALM cannot be compiled with the '''GNU Fortran compiler versions 4.8.X and older'''. To solve this issue, please update to a newer compiler. Typical error messages appear with function {{{C_SIZEOF}}}:
{{{
Error: 'x' argument of 'c_sizeof' intrinsic at (1) must be an interoperable data entity
}}}
of with function {{{C_LOC}}}:
{{{
Error: Argument 'array' to 'c_loc' at (1) must be an associated scalar POINTER
}}}

'''Cray Fortran : Version 8.5.6 and maybe other versions:'''\\
In case of compiler option {{{-eD}}} assignments in INTEGER and CHARACTER declaration statements, e.g.
{{{
   CHARACTER (LEN=30), DIMENSION(100) ::  string_a = 'initial string'
}}}
do not work if arrays have more than 9999 elements. Use options {{{-G0 -rl -m2 -Rbcdsp}}} instead.

'''Cray with programming environment  PrgEnv-cray/6.0.4'''
To prevent possible problems with in-lining, use compiler option {{{-hipa0}}}.

'''Intel Fortran: Version 16.0 and higher:'''\\
When using NetCDF4, floating divide by zero may appear within the first NetCDF library calls in case that the compiler option {{{-fpe0}}} has been used. In order to circumvent this problem, you may omit the {{{-fpe0}}} option (a poor workaround, because floating point errors within the PALM code won't be detected too), or you should install the NetCDF library with Intel compiler option {{{-fp-model strict}}} switched on.