<s>
HSL	B-Application
,	O
originally	O
the	O
Harwell	B-Application
Subroutine	I-Application
Library	I-Application
,	O
is	O
a	O
collection	O
of	O
Fortran	O
77	O
and	O
95	O
codes	O
that	O
address	O
core	O
problems	O
in	O
numerical	B-General_Concept
analysis	I-General_Concept
.	O
</s>
<s>
It	O
is	O
primarily	O
developed	O
by	O
the	O
Numerical	B-General_Concept
Analysis	I-General_Concept
Group	O
at	O
the	O
Rutherford	O
Appleton	O
Laboratory	O
with	O
contributions	O
from	O
other	O
experts	O
in	O
the	O
field	O
.	O
</s>
<s>
HSL	B-Application
codes	O
are	O
easily	O
recognizable	O
by	O
the	O
format	O
of	O
their	O
names	O
,	O
consisting	O
of	O
two	O
letters	O
followed	O
by	O
two	O
numbers	O
,	O
dating	O
back	O
to	O
early	O
versions	O
of	O
Fortran	O
's	O
limited	O
subroutine	O
name	O
length	O
.	O
</s>
<s>
Original	O
development	O
of	O
the	O
Harwell	B-Application
Subroutine	I-Application
Library	I-Application
began	O
in	O
1963	O
by	O
Mike	O
Powell	O
and	O
Mike	O
Hopper	O
for	O
internal	O
use	O
on	O
an	O
IBM	O
mainframe	O
at	O
AERE	O
Harwell	O
.	O
</s>
<s>
Over	O
the	O
intervening	O
years	O
,	O
HSL	B-Application
has	O
striven	O
to	O
maintain	O
a	O
high	O
standard	O
of	O
reliability	O
and	O
has	O
garnered	O
a	O
worldwide	O
reputation	O
as	O
a	O
prime	O
source	O
of	O
numerical	O
software	O
.	O
</s>
<s>
It	O
has	O
undergone	O
a	O
number	O
of	O
changes	O
to	O
reflect	O
newly	O
available	O
features	O
of	O
the	O
Fortran	O
language	O
,	O
completing	O
in	O
1990	O
the	O
conversion	O
to	O
Fortran	O
77	O
,	O
and	O
more	O
recently	O
,	O
the	O
entire	O
Library	O
has	O
been	O
made	O
thread	B-Operating_System
safe	I-Operating_System
.	O
</s>
<s>
Many	O
older	O
codes	O
have	O
now	O
been	O
superseded	O
and	O
are	O
available	O
in	O
the	O
HSL	B-Application
Archive	O
.	O
</s>
<s>
The	O
current	O
version	O
,	O
HSL	B-Application
2007	O
is	O
a	O
commercial	O
product	O
sold	O
by	O
AspenTech	O
,	O
but	O
is	O
also	O
available	O
without	O
charge	O
to	O
individual	O
academics	O
direct	O
from	O
STFC	O
for	O
teaching	O
and	O
their	O
own	O
academic	O
research	O
purposes	O
.	O
</s>
<s>
Obsolete	O
routines	O
are	O
stored	O
in	O
the	O
HSL	B-Application
archive	O
and	O
are	O
available	O
for	O
personal	O
non-commercial	O
use	O
by	O
anyone	O
following	O
registration	O
with	O
HSL	B-Application
.	O
</s>
