Use some vector manipulation package as for instance Math::Vector::Real (that I have just uploaded to CPAN!): 
use Math::Vector::Real;

my $l0 = V(?, ?);
my $l1 = V(?, ?);
my $p = V(?, ?);

my $u = $l1 - $l0;
$u /= abs($u);

my $n = $p - $l0;
$n -= ($n * $u) * $u;
printf "distance is %d\n", abs($n);

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In reply to Re: perl module or code for calculating the shortest distance between a line and a point (vector linear algebra) by salva
in thread perl module or code for calculating the shortest distance between a line and a point (vector linear algebra) by fraizerangus

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