<s>
In	O
computational	O
geometry	O
,	O
the	O
fixed-radius	O
near	O
neighbor	O
problem	O
is	O
a	O
variant	O
of	O
the	O
nearest	B-Algorithm
neighbor	I-Algorithm
search	I-Algorithm
problem	O
.	O
</s>
<s>
A	O
hash	B-Algorithm
table	I-Algorithm
can	O
be	O
used	O
to	O
find	O
,	O
for	O
each	O
input	O
point	O
,	O
the	O
other	O
inputs	O
that	O
are	O
mapped	O
to	O
nearby	O
grid	O
points	O
,	O
which	O
can	O
then	O
be	O
tested	O
for	O
whether	O
their	O
unrounded	O
positions	O
are	O
actually	O
within	O
distanceΔ	O
.	O
</s>
<s>
The	O
fixed-radius	B-Algorithm
near	I-Algorithm
neighbors	I-Algorithm
problem	O
arises	O
in	O
continuous	O
Lagrangian	O
simulations	O
(	O
such	O
as	O
smoothed	O
particle	O
hydrodynamics	O
)	O
,	O
computational	O
geometry	O
,	O
and	O
point	O
cloud	O
problems	O
(	O
surface	O
reconstructions	O
)	O
.	O
</s>
