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#!/usr/bin/env perl
use v5.24;
use warnings;
use experimental 'signatures';
no warnings 'experimental::signatures';
my @points = map {[split m{\D+}]} grep { /\S/ } split m{\s+}mxs, '
333,129 39,189 140,156 292,134 393,52 160,166 362,122 13,193
341,104 320,113 109,177 203,152 343,100 225,110 23,186 282,102
284,98 205,133 297,114 292,126 339,112 327,79 253,136 61,169
128,176 346,72 316,103 124,162 65,181 159,137 212,116 337,86
215,136 153,137 390,104 100,180 76,188 77,181 69,195 92,186
275,96 250,147 34,174 213,134 186,129 189,154 361,82 363,89
';
my ($m, $q) = lse(@points);
my $xmin = my $xmax = $points[0][0];
for my $p (@points) {
my ($x, $y) = $p->@*;
if ($x < $xmin) { $xmin = $x }
elsif ($x > $xmax) { $xmax = $x }
say "$x,$y";
}
my ($ymin, $ymax) = map { $m * $_ + $q } ($xmin, $xmax);
say "$xmin,$ymin,$xmax,$ymax";
sub lse (@points) {
my ($N, $X, $Y, $X2, $XY) = (scalar(@points), (0) x 4);
for my $p (@points) {
my ($x, $y) = $p->@*;
$X += $x;
$Y += $y;
$X2 += $x * $x;
$XY += $x * $y;
}
my $den = $N * $X2 - $X * $X;
my $m = ($N * $XY - $X * $Y) / $den;
my $q = ($X2 * $Y - $X * $XY) / $den;
return ($m, $q);
}
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