Multi tool use

Clash Royale CLAN TAG

Shortest distance from GPS point to a great circle inconsistency

I have followed a few links form both here on stackoverflow and also around the internet and have in turn created some functions for crosstrack distance. However i think i am missing something as the calculations are inconsistent.

From the following link https://www.movable-type.co.uk/scripts/latlong.html shown in another answer here Minimum distance between a point and a line in latitude, longitude i have created what i thought were the functions needed for the calculation as shown below.

public function distanceTo($from, $to) {
//Calculate point differences
$latc = floatval($to->getRadialLatitude() - $from->getRadialLatitude());
$lngc = floatval($to->getRadialLongitude() - $from->getRadialLongitude());

//Calculate a
$a = sin($latc/2) * sin($latc/2) + cos($from->getRadialLatitude()) *
cos($to->getRadialLatitude()) * sin($lngc/2) * sin($lngc/2);

//Calculate c
$c = 2 * atan2(sqrt($a), sqrt(1-$a));

//Calculate d
$d = 6371000 * $c;

return $d;
}

public function bearingTo($pa, $pb) {
//Convert to rads
$lata = $pa->getRadialLatitude();
$latb = $pb->getRadialLatitude();
$lngc = floatval(($pb->getDecimalLongitude() - $pa->getDecimalLongitude()) * (pi() / 180));

//Calculate y
$y = sin($lngc) * cos($latb);

//Calulate x
$x = cos($lata) * sin($latb) - sin($lata) * cos($latb) * cos($lngc);

//Calculate 0
$b = atan2($y, $x) * (180 / pi());

return fmod(($b + 360), 360);
}

public function crossTrackDistance($pc, $pa, $pb) {
$a = floatval($this->distanceTo($pa, $pc) / 6371000);

$b = floatval($this->bearingTo($pa, $pc) * (pi() / 180));

$c = floatval($this->bearingTo($pa, $pb) * (pi() / 180));

$d = asin(sin($a) * sin($b - $c));

return $d * 6371000;
}


These functions return the correct value for certain point line combinations for example,
point -37.756047854746626,175.37913657724857

line-37.75967614891693,175.38304656744003
-37.759917887500336,175.38264960050583

which is returning 529.37651757282m which seems okay as an estimation using google maps shows the distance as about 530m.

529.37651757282m

However this is where my issue lies with the
point -38.66714197682136,176.14404257386923
and the
line -38.6661326,176.1452709,-38.6660406,176.1453836 i am getting a distance of 0.51372771654236m which is obviously very very far off as it is around 150m

-38.66714197682136,176.14404257386923

-38.6661326,176.1452709,-38.6660406,176.1453836

0.51372771654236m

Any help as to where the issue is would be very helpful

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