<s>
In	O
coding	B-Error_Name
theory	I-Error_Name
,	O
the	O
Forney	B-Error_Name
algorithm	I-Error_Name
(	O
or	O
Forney	B-Error_Name
's	I-Error_Name
algorithm	I-Error_Name
)	O
calculates	O
the	O
error	O
values	O
at	O
known	O
error	O
locations	O
.	O
</s>
<s>
However	O
,	O
there	O
is	O
a	O
more	O
efficient	O
method	O
known	O
as	O
the	O
Forney	B-Error_Name
algorithm	I-Error_Name
,	O
which	O
is	O
based	O
on	O
Lagrange	O
interpolation	O
.	O
</s>
<s>
gives	O
a	O
derivation	O
of	O
the	O
Forney	B-Error_Name
algorithm	I-Error_Name
.	O
</s>
