<?php
$lat1 = $_REQUEST['lat1'];
$long1 = $_REQUEST['long1'];
$lat2 = $_REQUEST['lat2'];
$long2 = $_REQUEST['long2'];
$d = distance_cartesian($lat1, $long1, $lat2, $long2);
print "cartesian distance: $d\n";
$d = distance_cartesian_modified($lat1, $long1, $lat2, $long2);
print "cosine modified cartesian distance: $d\n";
$d = distance_spherical($lat1, $long1, $lat2, $long2);
print "spherical trig distance: $d\n";
#cartesian distance
function distance_cartesian($lat1, $long1, $lat2, $long2) {
$d = sqrt( pow($long1-$long2, 2) + pow($lat1-$lat2, 2) );
return $d * 69;
}
# modified cartesian distance
function distance_cartesian_modified($lat1, $long1, $lat2, $long2) {
$d = sqrt(
pow(
($long1 - $long2)
* cos(
(($lat1 + $lat2) / 2) / 180 * M_PI
)
, 2)
+ pow(($lat1-$lat2), 2)
) * 69;
return $d;
}
function acos($n) {
return atan2( sqrt(1 - $n * $n), $n);
}
# convert degres to radians
function deg2rad($n) {
return $n / 180 * M_PI;
}
# spherical distance
function distance_spherical($lat1, $long1, $lat2, $long2) {
$lat1 = $lat1/180 * M_PI;
$long1 = $long1/180 * M_PI;
$lat2 = $lat2/180 * M_PI;
$long2 = $long2/180 * M_PI;
$a = $long1 - $long2;
if ($a < 0) {$a = -$a;}
if ($a > M_PI) {$a = 2 * M_PI;}
$d = acos(sin($lat2) * sin($lat1) + cos($lat2)*cos($lat1)*cos($a)) * 3958;
return $d;
}
/*
die "usage disttest lat1 long1 lat2 long2" unless (@ARGV == 4);
my ($lat1, $long1, $lat2, $long2) = @ARGV;
my $d1 = dist(@ARGV);
print "spherical trig distance: $d1\n";
$d2 = cdist(@ARGV);
print "cartesian distance: $d2\n";
$d3 = mcdist(@ARGV);
print "cosine modified cartesian distance: $d3\n";
#cartesian distance
sub cdist {
my ($lat1, $long1, $lat2, $long2) = @_;
$h = sqrt( ($long1-$long2)**2 + ($lat1-$lat2)**2 );
return $h * 69;
}
# modified cartesian distance
sub mcdist {
my ($lat1, $long1, $lat2, $long2) = @_;
# calc hyp
$h = sqrt( (($long1-$long2)* cos(deg2rad( ($lat1+$lat2)/2)))**2 + ( ($lat1-$lat2))**2 )*69;
return $h ;
}
sub acos {
#print STDERR " acos param: |@_| \n";
atan2( sqrt(1-$_[0] * $_[0]), $_[0])
}
# convert degres to radians
sub deg2rad {
my $n = shift;
$pi = atan2(1,1) * 4;
return $n/180 * $pi;
}
# spherical distance
sub dist {
$pi = atan2(1,1) * 4;
my @parms = @_;
my $lat1 = $parms[0]/180 * $pi ;
my $long1 = $parms[1]/180 * $pi;
my $lat2 = $parms[2]/180 * $pi;
my $long2 = $parms[3]/180 * $pi;
$a = $long1 - $long2;
if ($a < 0) {$a = -$a;}
if ($a > $pi) {$a = 2 * $pi;}
$d = acos(sin($lat2) * sin($lat1) + cos($lat2)*cos($lat1)*cos($a)) * 3958;
return $d ;
}
*/
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