<s>
STELLA	B-Language
(	O
short	O
for	O
Systems	B-Language
Thinking	I-Language
,	I-Language
Experimental	I-Language
Learning	I-Language
Laboratory	I-Language
with	I-Language
Animation	I-Language
;	O
also	O
marketed	O
as	O
iThink	B-Language
)	O
is	O
a	O
visual	B-Language
programming	I-Language
language	I-Language
for	O
system	O
dynamics	O
modeling	O
introduced	O
by	O
Barry	O
Richmond	O
in	O
1985	O
.	O
</s>
<s>
STELLA	B-Language
has	O
been	O
used	O
in	O
academia	O
as	O
a	O
teaching	O
tool	O
and	O
has	O
been	O
utilized	O
in	O
a	O
variety	O
of	O
research	O
and	O
business	O
applications	O
.	O
</s>
<s>
With	O
the	O
financial	O
support	O
of	O
Analog	O
Devices	O
,	O
Inc	O
.	O
and	O
technical	O
support	O
from	O
Apple	O
Computer	O
,	O
he	O
developed	O
STELLA	B-Language
(	O
short	O
for	O
Structural	O
Thinking	O
,	O
Experimental	O
Learning	O
Laboratory	O
with	O
Animation	O
)	O
at	O
his	O
company	O
.	O
</s>
<s>
He	O
presented	O
the	O
prototype	O
for	O
the	O
visual	B-Language
programming	I-Language
language	I-Language
in	O
1985	O
at	O
the	O
System	O
Dynamics	O
Society	O
's	O
annual	O
conference	O
in	O
a	O
paper	O
entitled	O
"	O
STELLA	B-Language
:	O
Software	O
for	O
Bringing	O
System	O
Dynamics	O
to	O
the	O
Other	O
98%	O
"	O
.	O
</s>
<s>
He	O
quoted	O
a	O
1994	O
paper	O
in	O
which	O
Richmond	O
described	O
STELLA	B-Language
as	O
"	O
quite	O
unique	O
,	O
quite	O
powerful	O
,	O
and	O
quite	O
broadly	O
useful	O
as	O
a	O
way	O
of	O
thinking	O
and	O
or	O
learning	O
.	O
</s>
<s>
STELLA	B-Language
's	O
approach	O
to	O
modeling	O
systems	O
shares	O
some	O
similarities	O
with	O
a	O
precursor	O
,	O
the	O
DYNAMO	B-Language
simulation	B-Language
language	I-Language
.	O
</s>
<s>
DYNAMO	B-Language
explicitly	O
defined	O
"	O
stocks	O
"	O
(	O
reservoirs	O
)	O
and	O
"	O
flows	O
"	O
(	O
inputs	O
and	O
outputs	O
)	O
as	O
key	O
variables	O
in	O
a	O
system	O
,	O
a	O
vocabulary	O
that	O
STELLA	B-Language
shares	O
.	O
</s>
<s>
Within	O
STELLA	B-Language
,	O
users	O
are	O
presented	O
with	O
a	O
graphical	B-Application
user	I-Application
interface	I-Application
in	O
which	O
they	O
may	O
create	O
graphical	O
models	O
of	O
a	O
system	O
using	O
four	O
fundamentals	O
:	O
stocks	O
,	O
flows	O
,	O
converters	O
,	O
and	O
connectors	O
.	O
</s>
<s>
STELLA	B-Language
does	O
not	O
differentiate	O
between	O
external	O
and	O
intermediate	O
variables	O
within	O
a	O
system	O
;	O
all	O
of	O
them	O
are	O
represented	O
with	O
converters	O
.	O
</s>
<s>
The	O
software	O
produces	O
finite	B-Algorithm
difference	I-Algorithm
equations	I-Algorithm
that	O
describe	O
the	O
graphical	O
model	O
and	O
allows	O
users	O
to	O
select	O
a	O
numerical	B-General_Concept
analysis	I-General_Concept
method	O
to	O
apply	O
to	O
the	O
system	O
,	O
either	O
the	B-Algorithm
Euler	I-Algorithm
method	I-Algorithm
or	O
various	O
Runge	B-Algorithm
–	I-Algorithm
Kutta	I-Algorithm
methods	I-Algorithm
(	O
either	O
second	O
or	O
fourth	O
order	O
)	O
.	O
</s>
<s>
STELLA	B-Language
can	O
output	O
data	O
in	O
graphical	O
or	O
tabular	O
forms	O
.	O
</s>
<s>
STELLA	B-Language
runs	O
one	O
window	O
at	O
a	O
time	O
,	O
meaning	O
that	O
only	O
one	O
model	O
can	O
be	O
run	O
at	O
any	O
given	O
moment	O
.	O
</s>
<s>
STELLA	B-Language
also	O
uses	O
the	O
emerging	O
XML-based	O
standard	O
for	O
storing	O
models	O
,	O
XMILE	O
.	O
</s>
<s>
In	O
2012	O
,	O
two	O
researchers	O
released	O
StellaR	O
,	O
software	O
which	O
can	O
translate	O
STELLA	B-Language
models	O
into	O
the	O
R	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
Because	O
of	O
its	O
simplicity	O
relative	O
to	O
more	O
complex	O
modeling	O
languages	O
,	O
STELLA	B-Language
has	O
been	O
cited	O
as	O
a	O
useful	O
tool	O
in	O
educational	O
settings	O
.	O
</s>
<s>
In	O
1987	O
,	O
High	O
Performance	O
Systems	O
released	O
a	O
guide	O
to	O
STELLA	B-Language
encouraging	O
its	O
use	O
in	O
academic	O
settings	O
and	O
numerous	O
textbooks	O
have	O
been	O
published	O
that	O
teach	O
modeling	O
and	O
systems	O
thinking	O
using	O
the	O
software	O
.	O
</s>
<s>
Sample	O
exercises	O
with	O
STELLA	B-Language
include	O
recreating	O
the	O
Daisyworld	O
model	O
,	O
simulating	O
the	O
Easter	O
Island	O
population	O
crash	O
,	O
and	O
modeling	O
the	O
protagonist	O
's	O
motivation	O
throughout	O
William	O
Shakespeare	O
's	O
Hamlet	B-Application
.	O
</s>
<s>
A	O
2010	O
study	O
of	O
the	O
efficacy	O
of	O
project-based	O
learning	O
upon	O
a	O
watershed-modeling	O
project	O
undertaken	O
by	O
72	O
middle	O
schoolers	O
found	O
that	O
the	O
addition	O
of	O
a	O
STELLA	B-Language
modeling	O
component	O
in	O
the	O
project	O
improved	O
overall	O
comprehension	O
of	O
the	O
material	O
over	O
traditional	O
methods	O
,	O
especially	O
among	O
female	O
students	O
who	O
outperformed	O
their	O
male	O
counterparts	O
with	O
the	O
addition	O
of	O
STELLA	B-Language
.	O
</s>
<s>
Among	O
other	O
projects	O
,	O
researchers	O
have	O
used	O
STELLA	B-Language
to	O
apply	O
Hubbert	O
peak	O
theory	O
to	O
the	O
Chinese	O
coal	O
supply	O
,	O
to	O
model	O
atrazine	O
dynamics	O
within	O
agricultural	O
lands	O
,	O
and	O
to	O
simulate	O
the	O
interactions	O
between	O
marine	O
macroinvertebrates	O
.	O
</s>
<s>
isee	O
systems	O
markets	O
an	O
identical	O
software	O
targeted	O
at	O
business	O
consumers	O
under	O
the	O
name	O
iThink	B-Language
(	O
previously	O
STELLA	B-Language
for	O
Business	O
)	O
.	O
</s>
<s>
iThink	B-Language
models	O
have	O
been	O
applied	O
to	O
a	O
variety	O
of	O
systems	O
including	O
manufacturing	O
lines	O
,	O
hospital	O
waste	O
in	O
developing	O
nations	O
,	O
coordination	O
between	O
an	O
emergency	O
room	O
and	O
hospital	O
beds	O
,	O
and	O
competition	O
in	O
the	O
home	O
video	O
market	O
.	O
</s>
<s>
In	O
a	O
1987	O
review	O
of	O
the	O
program	O
in	O
BioScience	O
,	O
Robert	O
Costanza	O
wrote	O
that	O
"	O
STELLA	B-Language
is	O
a	O
solid	O
program	O
–	O
well	O
planned	O
and	O
executed	O
–	O
that	O
breaks	O
new	O
ground.	O
"	O
</s>
<s>
A	O
1991	O
review	O
of	O
iThink	B-Language
in	O
Planning	O
Review	O
noted	O
that	O
the	O
software	O
's	O
strength	O
was	O
in	O
its	O
low	O
cost	O
(	O
the	O
program	O
retailed	O
at	O
around	O
$450	O
(	O
US$	O
in	O
dollars	O
)	O
and	O
the	O
vast	O
number	O
of	O
possibilities	O
allowed	O
by	O
its	O
open-ended	O
form	O
.	O
</s>
