<s>
The	O
Pencil	B-Operating_System
Code	I-Operating_System
is	O
a	O
high-order	O
finite-difference	B-Algorithm
code	I-Algorithm
for	O
solving	O
partial	O
differential	O
equations	O
,	O
written	O
in	O
Fortran	B-Language
95	I-Language
.	O
</s>
<s>
The	O
code	O
is	O
designed	O
for	O
efficient	O
computation	O
with	O
massive	O
parallelization	B-Operating_System
.	O
</s>
<s>
Due	O
to	O
its	O
modular	O
structure	O
,	O
it	O
can	O
be	O
used	O
for	O
a	O
large	O
variety	O
of	O
physical	O
setups	O
like	O
hydro	O
-	O
and	O
magnetohydrodynamics	O
relevant	O
for	O
,	O
e.g.	O
,	O
astrophysics	O
,	O
geophysics	O
,	O
cosmology	O
,	O
turbulence	O
,	O
and	O
combustion	B-Application
.	O
</s>
<s>
Pencil	B-Operating_System
Code	I-Operating_System
is	O
free	B-Application
software	I-Application
released	O
under	O
the	O
GNU	B-License
GPL	I-License
v2	O
.	O
</s>
<s>
The	O
computational	O
scheme	O
is	O
finite-difference	B-Algorithm
and	O
non-conservative	O
;	O
the	O
time	O
integration	O
is	O
implemented	O
by	O
an	O
explicit	O
scheme	O
.	O
</s>
<s>
High-order	O
(	O
4th	O
,	O
6th	O
,	O
and	O
10th	O
order	O
,	O
as	O
well	O
as	O
single-sided	O
or	O
upwind	O
)	O
derivatives	B-Algorithm
are	O
available	O
to	O
resolve	O
strong	O
variations	O
on	O
the	O
grid	O
scale	O
.	O
</s>
<s>
MPI	B-Application
is	O
used	O
for	O
parallelization	B-Operating_System
,	O
but	O
the	O
code	O
can	O
also	O
be	O
run	O
non-parallel	O
on	O
a	O
simple	O
PC	B-Device
.	O
</s>
<s>
three-step	O
Runge	B-Algorithm
–	I-Algorithm
Kutta	I-Algorithm
)	O
,	O
treatment	O
of	O
shocks	O
,	O
embedded	O
particle	O
dynamics	O
,	O
chemistry	O
,	O
massive	O
parallel	B-Operating_System
I/O	I-Operating_System
,	O
etc	O
.	O
</s>
<s>
The	O
Pencil	B-Operating_System
Code	I-Operating_System
has	O
mainly	O
been	O
applied	O
to	O
describe	O
compressible	O
turbulence	O
and	O
resistive	O
magnetohydrodynamics	O
.	O
</s>
<s>
Applications	O
include	O
studies	O
of	O
planet	O
formation	O
,	O
the	O
solar	O
dynamo	O
,	O
mono-chromatic	O
radiative	O
transfer	O
,	O
the	O
coronal	O
heating	O
problem	O
,	O
debris	O
disks	O
,	O
turbulent	O
combustion	B-Application
of	O
solid	O
fuels	O
,	O
and	O
others	O
.	O
</s>
<s>
The	O
Pencil	B-Operating_System
Code	I-Operating_System
development	O
was	O
started	O
in	O
2001	O
by	O
Axel	O
Brandenburg	O
and	O
Wolfgang	O
Dobler	O
during	O
the	O
'	O
Helmholtz	O
Summer	O
School	O
 '	O
at	O
the	O
Helmholtz	O
Research	O
Centre	O
for	O
Geosciences	O
in	O
Potsdam	O
.	O
</s>
<s>
The	O
code	O
repository	O
was	O
hosted	O
at	O
NORDITA	O
until	O
2008	O
and	O
was	O
then	O
moved	O
to	O
Google	B-Application
Developers	I-Application
.	O
</s>
<s>
In	O
April	O
2015	O
the	O
code	O
was	O
migrated	O
to	O
GitHub	B-Application
.	O
</s>
<s>
Since	O
June	O
2018	O
the	O
Pencil	B-Operating_System
Code	I-Operating_System
supports	O
the	O
HDF5	B-Application
data	O
format	O
.	O
</s>
