Initial Bearing Calculation error in PHP

<?php
 
 
	    function Heading($lat1, $long1, $lat2, $long2) {
	       // Takes lat/longs as expressions in Degrees
	       $pi = 3.14159265358979;
	       $rLat1 = 0.0;
	       $rLong1 = 0.0;
	       $rLat2 = 0.0;
	       $rLong2 = 0.0;
	       $d = 0.0;
	       $h = 0.0;
	       $result = 0.0;
 
	       $rLat1 = deg2rad($lat1);
	       $rLong1 = deg2rad($long1);
 
	       $rLat2 = deg2rad($lat2);
	       $rLong2 = deg2rad($long2);
 
 
	       // Distance in Meters Using Radians
	       // Less subject to rounding errors for small distances
	        $d = ( 2 * asin(sqrt(pow(sin(($rLat1 - $rLat2) / 2), 2) + cos($rLat1) * cos($rLat2) * pow(sin(($rLong1 - $rLong2) / 2),2))));
                
                // subtracting the acos from 2 * pi does the same as the MOD 360 calculation
                if (($long2 - $long1) < 0) {
 
                        // if we're going to pass acos a value greater than 1, then just pass 1
                        if (((((sin($rLat2) - sin($rLat1)) * cos($d)) / (sin($d) * cos($rLat1)))) > 1) {
                                $h = 2 * $pi - acos(1);
                           }
                        else {
                                // if we're going to pass acos a value < -1, then just pass -1
                                if (((((sin($rLat2) - sin($rLat1)) * cos($d)) / (sin($d) * cos($rLat1)))) < -1) {
	                                $h = 2 * $pi - acos(-1);
                                   }
                                else {
	                                $h = 2 * $pi - acos(((sin($rLat2) - sin($rLat1)) * cos($d)) / (sin($d) * cos($rLat1)));
                                }
                        }
                   }
                else {
                        // if we're going to pass acos a value greater than 1, then just pass 1
                        if (((((sin($rLat2) - sin($rLat1)) * cos($d)) / (sin($d) * cos($rLat1)))) > 1) {
                             $h = acos(1);
                           }
                        else {
                                // if we're going to pass acos a value < -1, then just pass -1
                                if (((((sin($rLat2) - sin($rLat1)) * cos($d)) / (sin($d) * cos($rLat1)))) < -1) {
                                        $h = acos(-1);
                                   }
                                else {
                                        $h = acos(((sin($rLat2) - sin($rLat1)) * cos($d)) / (sin($d) * cos($rLat1)));
                                }
                        }
                }
 
              
               // Was still having trouble with purely North/South movement, so tried this
               // it works, but there are still errors if the course is just slightly East or West of North/South
               if ($long2 == $long1) {
                   if ($lat1 >= $lat2) {
                      $result = rad2deg(3.14159265358979);
                      }
                   else {
                      $result = rad2deg(0);
                      }
                  }
               else {
	           $result = rad2deg($h);
                  }
 
 
 
	       return($result);
	    }
 
 
 
	 $dHeading = number_format(Heading(30, -30, 30, -20));
         echo "heading east in the northern/western hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(30, -20, 30, -30));
         echo "heading west in the northern/western hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(30, -30, 40, -30));
         echo "heading north in the northern/western hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(40, -30, 30, -30));
         echo "heading south in the northern/western hemisphere: ".$dHeading."<p>";
 
 
	 $dHeading = number_format(Heading(30, 30, 30, 40));
         echo "heading east in the northern/eastern hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(30, 40, 30, 30));
         echo "heading west in the northern/eastern hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(30, 30, 40, 30));
         echo "heading north in the northern/eastern hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(40, 30, 30, 31));
         echo "heading south in the northern/eastern hemisphere: ".$dHeading."<p>";
 
 
	 $dHeading = number_format(Heading(-30, -30, -30, -20));
         echo "heading east in the southern/western hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(-30, -20, -30, -30));
         echo "heading west in the southern/western hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(-30, -30, -20, -30));
         echo "heading north in the southern/western hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(-20, -30, -30, -30));
         echo "heading south in the southern/western hemisphere: ".$dHeading."<p>";
 
 
	 $dHeading = number_format(Heading(-30, 30, -30, 40));
         echo "heading east in the southern/eastern hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(-30, 40, -30, 30));
         echo "heading west in the southern/eastern hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(-30, 30, -20, 30));
         echo "heading north in the southern/eastern hemisphere: ".$dHeading."<br>";
 
// This one is still coming out wrong because I added a little East movement... 
// course should probably be about 179 but comes out 162
 
	 $dHeading = number_format(Heading(-20, 30, -30, 31));
         echo "heading south in the southern/eastern hemisphere: ".$dHeading."<p>";
 
 
 
     ?>

                                              

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<?php
 
 
	    function Heading($lat1, $long1, $lat2, $long2) {
	       // Takes lat/longs as expressions in Degrees
	       $pi = 3.14159265358979;
	       $rLat1 = 0.0;
	       $rLong1 = 0.0;
	       $rLat2 = 0.0;
	       $rLong2 = 0.0;
	       $d = 0.0;
	       $h = 0.0;
	       $result = 0.0;
 
	       $rLat1 = deg2rad($lat1);
	       $rLong1 = deg2rad($long1);
 
	       $rLat2 = deg2rad($lat2);
	       $rLong2 = deg2rad($long2);
 
 
	       // Distance in Meters Using Radians
	       // Less subject to rounding errors for small distances
	        $d = ( 2 * asin(sqrt(pow(sin(($rLat1 - $rLat2) / 2), 2) + cos($rLat1) * cos($rLat2) * pow(sin(($rLong1 - $rLong2) / 2),2))));
                
                // subtracting the acos from 2 * pi does the same as the MOD 360 calculation
	        //if (sin(ABS($rLong2) - ABS($rLong1)) < 0) {
 
                if (($long2 - $long1) < 0) {
                      $h = 2 * $pi - acos((sin($rLat2) - (sin($rLat1) * cos($d))) / (sin($d) * cos($rLat1)));
                   }
                else {
                      $h = acos((sin($rLat2) - (sin($rLat1) * cos($d))) / (sin($d) * cos($rLat1)));
                }
              
 
               $result = rad2deg($h);
 
 
	       return($result);
	    }
 
            function HeadingNew($lat1, $long1, $lat2, $long2) {
               // Takes lat/longs as expressions in Degrees
               $pi = 3.14159265358979;
               $rLat1 = 0.0;
               $rLong1 = 0.0;
               $rLat2 = 0.0;
               $rLong2 = 0.0;
               $d = 0.0;
               $h = 0.0;
               $result = 0.0;
 
               $rLat1 = deg2rad($lat1);
               $rLong1 = deg2rad($long1);
 
               $rLat2 = deg2rad($lat2);
               $rLong2 = deg2rad($long2);
 
 
                $d = deg2rad($long2 - $long1);
                $y = sin($d) * cos($rLat2);
                $x = cos($rLat1) * sin($rLat2) - sin($rLat1) * cos($rLat2) * cos($d);
                $h = atan2($y, $x);
                //echo "D = ".$d." X = ".$x." Y = ".$y." H = ".$h."<br>";
 
                //$result = rad2deg($h);
 
                $result = $h * (180/$pi);
                $result = ($result + 360) % 360;
 
               return($result);
            }
 
   
 
 
	 $dHeading = number_format(Heading(00, -30, 00, -20));
         echo "heading east in the equator/western hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(00, -20, 00, -30));
         echo "heading west in the equator/western hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(30, -30, 40, -30));
         echo "heading north in the northern/western hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(40, -30, 30, -30));
         echo "heading south in the northern/western hemisphere: ".$dHeading."<p>";
 
 
	 $dHeading = number_format(Heading(30, 30, 30, 40));
         echo "heading east in the northern/eastern hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(30, 40, 30, 30));
         echo "heading west in the northern/eastern hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(30, 30, 40, 30));
         echo "heading north in the northern/eastern hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(40, 30, 30, 31));
         echo "heading southeast in the northern/eastern hemisphere: ".$dHeading."<p>";
 
 
	 $dHeading = number_format(Heading(-30, -30, -30, -20));
         echo "heading east in the southern/western hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(-30, -20, -30, -30));
         echo "heading west in the southern/western hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(-30, -30, -20, -30));
         echo "heading north in the southern/western hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(-20, -30, -30, -30));
         echo "heading south in the southern/western hemisphere: ".$dHeading."<p>";
 
 
	 $dHeading = number_format(Heading(-30, 30, -30, 40));
         echo "heading east in the southern/eastern hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(-30, 40, -30, 30));
         echo "heading west in the southern/eastern hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(-30, 30, -20, 30));
         echo "heading north in the southern/eastern hemisphere: ".$dHeading."<br>";
	 $dHeading = number_format(Heading(-20, 30, -30, 31));
         echo "heading southeast in the southern/eastern hemisphere: ".$dHeading."<p>";
 
 
 
     ?>
  

                                              

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