This script/web page lets you calculate Geographical distance based on Latitude and Longitude. It does not compensate for the fact that the earth is fat in the middle. It does not take into account altitude. However, it is accurate enough for most applications.
function distance($Aa, $Ba, $Ca, $Da){ // this is just some basic error checking i'd normally put it into a seperate file but // for the purposes of this file... well you know. // The math for this was taken from http://mathforum.org/library/drmath/view/51711.html $input = array($Aa, $Ba, $Ca, $Da); foreach($input as $name){ if (ereg("[[:alpha:]]",$name)){ echo "You cannot enter letters into this function<br>\n"; die; } if(ereg("\.",$name)){ $dot = "."; $pos = strpos($name, $dot); //echo $pos." <br>\n"; if($pos > 3){ echo "The input cannot exceed more than 3 digits left of the decimal<br>\n"; die; } } if($name > 365){ echo "The input cannot exceed 365 degrees <BR>\n"; die;
} }
$A = $Aa/57.29577951; $B = $Ba/57.29577951; $C = $Ca/57.29577951; $D = $Da/57.29577951; //convert all to radians: degree/57.29577951
if ($A == $C && $B == $D ){ $dist = 0; } else if ( (sin($A)* sin($C)+ cos($A)* cos($C)* cos($B-$D)) > 1){ $dist = 3963.1* acos(1);// solved a prob I ran into. I haven't fully analyzed it yet
?> <body bgcolor="#FFFFFF" text="#000000"> <form name="form1" method="post" action=""> <p>Point one Lat <input type="text" name="LAT1" value="<?=$_POST[LAT1]?>" > Long <input type="text" name="LONG1" value="<?=$_POST[LONG1]?>"> </p> <p>Point two Lat <input type="text" name="LAT2" value="<?=$_POST[LAT2]?>"> Long <input type="text" name="LONG2" value="<?=$_POST[LONG2]?>"> </p> <p> <input type="submit" name="Submit" value="Submit"> </p> </form> <? echo "<br>distance = ".$distance." miles (as the crow flies)<br>"; ?> </body> </html>
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