<s>
Global	B-Library
Arrays	I-Library
,	O
or	O
GA	O
,	O
is	O
the	O
library	O
developed	O
by	O
scientists	O
at	O
Pacific	O
Northwest	O
National	O
Laboratory	O
for	O
parallel	B-Operating_System
computing	I-Operating_System
.	O
</s>
<s>
GA	O
provides	O
a	O
friendly	O
API	B-General_Concept
for	O
shared-memory	O
programming	O
on	O
distributed-memory	O
computers	O
for	O
multidimensional	O
arrays	O
.	O
</s>
<s>
The	O
GA	O
library	O
is	O
a	O
predecessor	O
to	O
the	O
GAS	O
(	O
global	B-Application
address	I-Application
space	I-Application
)	O
languages	O
currently	O
being	O
developed	O
for	O
high-performance	O
computing	O
.	O
</s>
<s>
Although	O
GA	O
was	O
initially	O
developed	O
to	O
run	O
with	O
TCGMSG	O
,	O
a	O
message	O
passing	O
library	O
that	O
came	O
before	O
the	O
MPI	O
standard	O
(	O
Message	B-Application
Passing	I-Application
Interface	I-Application
)	O
,	O
it	O
is	O
now	O
fully	O
compatible	O
with	O
MPI	O
.	O
</s>
<s>
GA	O
includes	O
simple	O
matrix	O
computations	O
(	O
matrix-matrix	O
multiplication	O
,	O
LU	O
solve	O
)	O
and	O
works	O
with	O
ScaLAPACK	B-Application
.	O
</s>
<s>
The	O
GA	O
library	O
is	O
incorporated	O
into	O
many	O
quantum	O
chemistry	O
packages	O
,	O
including	O
NWChem	B-Application
,	O
MOLPRO	B-Application
,	O
UTChem	O
,	O
MOLCAS	B-Application
,	O
and	O
TURBOMOLE	B-Application
.	O
</s>
<s>
The	O
GA	O
toolkit	O
is	O
free	B-Application
software	I-Application
,	O
licensed	O
under	O
a	O
.	O
</s>
