<s>
Unit	B-Application
generators	I-Application
(	O
or	O
ugens	O
)	O
are	O
the	O
basic	O
formal	O
units	O
in	O
many	O
MUSIC-N-style	O
computer	B-Language
music	I-Language
programming	I-Language
languages	I-Language
.	O
</s>
<s>
They	O
are	O
sometimes	O
called	O
opcodes	B-Language
(	O
particularly	O
in	O
Csound	B-Application
)	O
,	O
though	O
this	O
expression	O
is	O
not	O
accurate	O
in	O
that	O
these	O
are	O
not	O
machine-level	O
instructions	O
.	O
</s>
<s>
Unit	B-Application
generators	I-Application
form	O
the	O
building	O
blocks	O
for	O
designing	O
synthesis	O
and	O
signal	O
processing	O
algorithms	O
in	O
software	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
simple	O
unit	B-Application
generator	I-Application
called	O
OSC	O
could	O
generate	O
a	O
sinusoidal	O
waveform	O
of	O
a	O
specific	O
frequency	O
(	O
given	O
as	O
an	O
input	O
or	O
argument	O
to	O
the	O
function	O
or	O
class	O
that	O
represents	O
the	O
unit	B-Application
generator	I-Application
)	O
.	O
</s>
<s>
ENV	O
could	O
be	O
a	O
unit	B-Application
generator	I-Application
that	O
delineates	O
a	O
breakpoint	O
function	O
.	O
</s>
<s>
Thus	O
ENV	O
could	O
be	O
used	O
to	O
drive	O
the	O
amplitude	B-Application
envelope	O
of	O
the	O
oscillator	O
OSC	O
through	O
the	O
equation	O
OSC*ENV	O
.	O
</s>
<s>
Unit	B-Application
generators	I-Application
often	O
use	O
predefined	O
arrays	O
of	O
values	O
for	O
their	O
functions	O
(	O
which	O
are	O
filled	O
with	O
waveforms	O
or	O
other	O
shapes	O
by	O
calling	O
a	O
specific	O
generator	O
function	O
)	O
.	O
</s>
<s>
The	O
unit	B-Application
generator	I-Application
theory	O
of	O
sound	O
synthesis	O
was	O
first	O
developed	O
and	O
implemented	O
by	O
Max	O
Mathews	O
and	O
his	O
colleagues	O
at	O
Bell	O
Labs	O
in	O
the	O
1950s	O
.	O
</s>
<s>
In	O
the	O
SuperCollider	B-Application
language	O
,	O
the	O
.ar	O
method	B-Language
in	O
the	O
SinOsc	O
class	O
is	O
a	O
UGen	O
that	O
generates	O
a	O
sine	O
wave	O
.	O
</s>
<s>
The	O
example	O
below	O
makes	O
a	O
sine	O
wave	O
at	O
frequency	O
440	O
,	O
phase	O
0	O
,	O
and	O
amplitude	B-Application
0.5	O
.	O
</s>
