PHP cos函数代码示例

 public function attackEntity(Entity $player)
 {
     if ($this->attackDelay > 30 && mt_rand(1, 32) < 4 && $this->distanceSquared($player) <= 200) {
         $this->attackDelay = 0;
         $f = 2;
         $yaw = $this->yaw + mt_rand(-220, 220) / 10;
         $pitch = $this->pitch + mt_rand(-120, 120) / 10;
         $nbt = new CompoundTag("", ["Pos" => new ListTag("Pos", [new DoubleTag("", $this->x + -sin($yaw / 180 * M_PI) * cos($pitch / 180 * M_PI) * 2), new DoubleTag("", $this->y + 2), new DoubleTag("", $this->z + cos($yaw / 180 * M_PI) * cos($pitch / 180 * M_PI) * 2)]), "Motion" => new ListTag("Motion", [new DoubleTag("", -sin($yaw / 180 * M_PI) * cos($pitch / 180 * M_PI)), new DoubleTag("", -sin($pitch / 180 * M_PI) * $f), new DoubleTag("", cos($yaw / 180 * M_PI) * cos($pitch / 180 * M_PI))]), "Rotation" => new ListTag("Rotation", [new FloatTag("", $yaw), new FloatTag("", $pitch)])]);
         $fireball = Entity::createEntity("FireBall", $this->chunk, $nbt, $this);
         if ($fireball instanceof FireBall) {
             $fireball->setExplode(true);
         }
         $fireball->setMotion($fireball->getMotion()->multiply($f));
         $ev = new EntityShootBowEvent($this, Item::get(Item::ARROW, 0, 1), $fireball, $f);
         $this->server->getPluginManager()->callEvent($ev);
         $projectile = $ev->getProjectile();
         if ($ev->isCancelled()) {
             $projectile->kill();
         } elseif ($projectile instanceof Projectile) {
             $this->server->getPluginManager()->callEvent($launch = new ProjectileLaunchEvent($projectile));
             if ($launch->isCancelled()) {
                 $projectile->kill();
             } else {
                 $projectile->spawnToAll();
                 $this->level->addSound(new LaunchSound($this), $this->getViewers());
             }
         }
     }
 }

function bearing($lat1, $lon1, $lat2, $lon2)
{
    if (round($lon1, 1) == round($lon2, 1)) {
        if ($lat1 < $lat2) {
            $bearing = 0;
        } else {
            $bearing = 180;
        }
    } else {
        $dist = distance($lat1, $lon1, $lat2, $lon2, 'N');
        $arad = acos((sin(deg2rad($lat2)) - sin(deg2rad($lat1)) * cos(deg2rad($dist / 60))) / (sin(deg2rad($dist / 60)) * cos(deg2rad($lat1))));
        $bearing = $arad * 180 / pi();
        if (sin(deg2rad($lon2 - $lon1)) < 0) {
            $bearing = 360 - $bearing;
        }
    }
    $dirs = array("N", "E", "S", "W");
    $rounded = round($bearing / 22.5) % 16;
    if ($rounded % 4 == 0) {
        $dir = $dirs[$rounded / 4];
    } else {
        $dir = $dirs[2 * floor((floor($rounded / 4) + 1) % 4 / 2)];
        $dir .= $dirs[1 + 2 * floor($rounded / 8)];
        #if ($rounded % 2 == 1)
        #  $dir = $dirs[round_to_int($rounded/4) % 4] . "-" . $dir;
    }
    $var_dist = "";
    #return $dir;
    if (isset($dist)) {
        $var_dist = $dist . " miles";
    }
    return round($bearing, 0) . "&#186; " . $dir . " " . $var_dist;
}

 public static function getRange($params)
 {
     if (empty($params['range'])) {
         $params['range'] = 1000;
     }
     if (!isset($params['latitude']) || !isset($params['longitude']) || !isset($params['range'])) {
         return false;
     }
     $latitude = $params['range'] / 111319.55;
     $result['min_latitude'] = number_format($params['latitude'] - $latitude, 6);
     $result['max_latitude'] = number_format($params['latitude'] + $latitude, 6);
     //	$longitude = $params['range']/(111319.55*cos($params['latitude']))*0.817;//0.86修正数
     $longitude = rad2deg(asin(sin($params['range'] / self::R) / cos(deg2rad($params['latitude']))));
     $result['min_longitude'] = number_format($params['longitude'] - $longitude, 6);
     $result['max_longitude'] = number_format($params['longitude'] + $longitude, 6);
     if ($result['min_latitude'] < -90) {
         $result['min_latitude'] = -90.0;
     }
     if ($result['max_latitude'] > 90) {
         $result['max_latitude'] = 90.0;
     }
     if ($result['min_longitude'] < -180) {
         $result['min_longitude'] = -180.0;
     }
     if ($result['max_longitude'] > 180) {
         $result['max_longitude'] = 180.0;
     }
     return $result;
 }

 protected function _createPie($parameter)
 {
     $step = ($parameter['end'] - $parameter['start']) / $parameter['detail'];
     // center
     $centerTop = new Image_3D_Point(0, 0, 0.5);
     $centerBottom = new Image_3D_Point(0, 0, -0.5);
     // Add polygones for top and bottom of the pie
     $x = cos($parameter['start']) * $parameter['outside'];
     $y = sin($parameter['start']) * $parameter['outside'];
     $top = new Image_3D_Point($x, $y, 0.5);
     $bottom = new Image_3D_Point($x, $y, -0.5);
     // Polygones for the opening side
     $this->_addPolygon(new Image_3D_Polygon($top, $centerTop, $centerBottom));
     $this->_addPolygon(new Image_3D_Polygon($bottom, $top, $centerBottom));
     for ($i = 1; $i <= $parameter['detail']; $i++) {
         $x = cos($parameter['start'] + $i * $step) * $parameter['outside'];
         $y = sin($parameter['start'] + $i * $step) * $parameter['outside'];
         $newTop = new Image_3D_Point($x, $y, 0.5);
         $newBottom = new Image_3D_Point($x, $y, -0.5);
         $this->_addPolygon(new Image_3D_Polygon($centerTop, $top, $newTop));
         $this->_addPolygon(new Image_3D_Polygon($centerBottom, $bottom, $newBottom));
         // Rand
         $this->_addPolygon(new Image_3D_Polygon($top, $newBottom, $newTop));
         $this->_addPolygon(new Image_3D_Polygon($top, $bottom, $newBottom));
         $top = $newTop;
         $bottom = $newBottom;
     }
     // Polygones for the closing side
     $this->_addPolygon(new Image_3D_Polygon($top, $centerTop, $centerBottom));
     $this->_addPolygon(new Image_3D_Polygon($bottom, $top, $centerBottom));
 }

    public function scopeNearLatLong($query, $lat, $lng, $radius = 10, $unit = 69.0)
    {
        if (!is_numeric($lat) || -90 >= $lat || $lat >= 90) {
            throw new RangeException("Latitude must be between -90 and 90 degrees.");
        }
        if (!is_numeric($lng) || -180 >= $lng || $lng >= 180) {
            throw new RangeException("Longitude must be between -180 and 180 degrees.");
        }
        $subQuery = clone $query;
        $latDistance = $radius / $unit;
        $latNorth = $lat - $latDistance;
        $latSouth = $lat + $latDistance;
        $lngDistance = $radius / ($unit * cos(deg2rad($lat)));
        $lngEast = $lng - $lngDistance;
        $lngWest = $lng + $lngDistance;
        $subQuery->selectRaw(DB::raw('*, (? * DEGREES(
			ACOS(
				  COS(RADIANS(?)) * COS(RADIANS(latitude)) * COS(RADIANS(? - longitude))
				+ SIN(RADIANS(?)) * SIN(RADIANS(latitude))
			)
		)) AS distance'))->addBinding([$unit, $lat, $lng, $lat], 'select');
        $subQuery->whereBetween('latitude', [$latNorth, $latSouth]);
        $subQuery->whereBetween('longitude', [$lngEast, $lngWest]);
        $query->from(DB::raw('(' . $subQuery->toSql() . ') as d'));
        $query->mergeBindings($subQuery->getQuery());
        $query->where('distance', '<=', $radius);
        // // To use:
        // $latitude  =  29.443778;
        // $longitude = -98.478903;
        // // Default radius is 10; default unit is miles.
        // Model::nearLatLong($latitude, $longitude)->get();
    }

 /**
  * Convert this UTM reference to a latitude and longitude
  *
  * @return the converted latitude and longitude
  */
 function toLatLng()
 {
     $wgs84 = new ReferenceEllipsoid(ReferenceEllipsoid::WGS84_MAJ, ReferenceEllipsoid::WGS84_MIN);
     $UTM_F0 = 0.9996;
     $a = $wgs84->maj;
     $eSquared = $wgs84->ecc;
     $ePrimeSquared = $eSquared / (1.0 - $eSquared);
     $e1 = (1 - sqrt(1 - $eSquared)) / (1 + sqrt(1 - $eSquared));
     $x = $this->easting - 500000.0;
     $y = $this->northing;
     $zoneNumber = $this->lngZone;
     $zoneLetter = $this->latZone;
     $longitudeOrigin = ($zoneNumber - 1.0) * 6.0 - 180.0 + 3.0;
     // Correct y for southern hemisphere
     if (ord($zoneLetter) - ord("N") < 0) {
         $y -= 10000000.0;
     }
     $m = $y / $UTM_F0;
     $mu = $m / ($a * (1.0 - $eSquared / 4.0 - 3.0 * $eSquared * $eSquared / 64.0 - 5.0 * pow($eSquared, 3.0) / 256.0));
     $phi1Rad = $mu + (3.0 * $e1 / 2.0 - 27.0 * pow($e1, 3.0) / 32.0) * sin(2.0 * $mu) + (21.0 * $e1 * $e1 / 16.0 - 55.0 * pow($e1, 4.0) / 32.0) * sin(4.0 * $mu) + 151.0 * pow($e1, 3.0) / 96.0 * sin(6.0 * $mu);
     $n = $a / sqrt(1.0 - $eSquared * sin($phi1Rad) * sin($phi1Rad));
     $t = tan($phi1Rad) * tan($phi1Rad);
     $c = $ePrimeSquared * cos($phi1Rad) * cos($phi1Rad);
     $r = $a * (1.0 - $eSquared) / pow(1.0 - $eSquared * sin($phi1Rad) * sin($phi1Rad), 1.5);
     $d = $x / ($n * $UTM_F0);
     $latitude = ($phi1Rad - $n * tan($phi1Rad) / $r * ($d * $d / 2.0 - (5.0 + 3.0 * $t + 10.0 * $c - 4.0 * $c * $c - 9.0 * $ePrimeSquared) * pow($d, 4.0) / 24.0 + (61.0 + 90.0 * $t + 298.0 * $c + 45.0 * $t * $t - 252.0 * $ePrimeSquared - 3.0 * $c * $c) * pow($d, 6.0) / 720.0)) * (180.0 / pi());
     $longitude = $longitudeOrigin + ($d - (1.0 + 2.0 * $t + $c) * pow($d, 3.0) / 6.0 + (5.0 - 2.0 * $c + 28.0 * $t - 3.0 * $c * $c + 8.0 * $ePrimeSquared + 24.0 * $t * $t) * pow($d, 5.0) / 120.0) / cos($phi1Rad) * (180.0 / pi());
     return new LatLng($latitude, $longitude);
 }

 /**
  * This function generates a pie chart of the given data.
  * It uses the technology provided by the {@link Chart} class to generate a pie chart from the given data.<br>
  * You can pass the following options to the this method  by using {@link Chart::get()}:<br>
  * * cx & cy - The coordinates of the center point of the pie chart.<br>
  * * r - The radius of the pie chart.
  * @param array An array of options, see {@link Chart::get()}.
  * @return string
  * @see Chart::get()
  */
 function get($options)
 {
     $cx = $options["cx"] ? $options["cx"] : 200;
     $cy = $options["cy"] ? $options["cy"] : 200;
     $r = $options["r"] ? $options["r"] : 150;
     $x1 = $cx;
     $y1 = $cy - $r;
     $alpha = 0;
     $output = "";
     $count = 0;
     $data = $this->chart->data;
     $sum = 0;
     foreach ($data as $obj) {
         $sum += $obj->value;
     }
     $colors = $this->chart->colors;
     foreach ($data as $obj) {
         $alpha = $alpha + $obj->percent / 100 * (2 * M_PI);
         $x2 = $cx + $r * sin($alpha);
         $y2 = $cy - $r * cos($alpha);
         $over180 = $obj->percent > 50 ? "1" : "0";
         $color = $this->chart->getColor($count);
         $output .= "<path d='M{$cx},{$cy} L{$x1},{$y1} A{$r},{$r} 0 {$over180},1 {$x2},{$y2} Z' fill='{$color}' opacity='0.6'/>\n\n";
         $x1 = $x2;
         $y1 = $y2;
         $count++;
     }
     if (isset($this->options["legend"])) {
         $x = $cx + $r * 1.2;
         $y = $cy - $r;
         $this->options["legend"]["x"] = $x;
         $this->options["legend"]["y"] = $y;
     }
     return $output;
 }

function AmbientTemperature($w, $ws, $METEO, $TIME)
{
    //Daily maximum and minimum temperatures
    if ($TIME['Ndays'] == 365) {
        //All year
        $TM = MonthlyAverageToAll($METEO['TMm']);
        $Tm = MonthlyAverageToAll($METEO['Tmm']);
    } elseif ($TIME['Ndays'] == 12) {
        //Only characteristic days
        $TM = $METEO['TMm'];
        $Tm = $METEO['Tmm'];
    }
    //Calculations
    for ($d = 0; $d < $TIME['Ndays']; $d++) {
        //Daily coefficients
        $a3[$d] = -pi() / ($ws[$d] + 2 * pi() - pi() / 6);
        $b3[$d] = -$a3[$d] * $ws[$d];
        $a4[$d] = pi() / ($ws[$d] - pi() / 6);
        $b4[$d] = -$a4[$d] * pi() / 6;
        $a5[$d] = pi() / (2 * pi() + $ws[$d] - pi() / 6);
        $b5[$d] = -(pi() + $a5[$d] * pi() / 6);
        for ($h = 0; $h < $TIME['Nsteps']; $h++) {
            if (-pi() < $w[$d][$h] && $w[$d][$h] < $ws[$d]) {
                $Ta[$d][$h] = $TM[$d] - ($TM[$d] - $Tm[$d]) / 2 * (1 + cos($a3[$d] * $w[$d][$h] + $b3[$d]));
            } elseif ($ws[$d] < $w[$d][$h] && $w[$d][$h] < pi() / 6) {
                $Ta[$d][$h] = $Tm[$d] + ($TM[$d] - $Tm[$d]) / 2 * (1 + cos($a4[$d] * $w[$d][$h] + $b4[$d]));
            } else {
                $Ta[$d][$h] = $TM[$d] - ($TM[$d] - $Tm[$d]) / 2 * (1 + cos($a5[$d] * $w[$d][$h] + $b5[$d]));
            }
        }
        //end FOR $h
    }
    //end FOREACH $d
    return $Ta;
}

 /**
  * Create a  Distance object
  *
  * @param	string	latitude of first point
  * @param	string	longitude of first point
  * @param	string	latitude2 of second point
  * @param	string	longitude2 of second point
  * @param	bool	True if the distance is in Kms, otherwise returns Miles
  */
 public function __construct($latitude = 0, $longitude = 0, $latitude2 = 0, $longitude2 = 0, $in_kms = TRUE)
 {
     $EARTH_RADIUS_MILES = 3963;
     // Miles
     $miles2kms = 1.609;
     $dist = 0;
     // Convert degrees to radians
     $latitude = $latitude * M_PI / 180;
     $longitude = $longitude * M_PI / 180;
     $latitude2 = $latitude2 * M_PI / 180;
     $longitude2 = $longitude2 * M_PI / 180;
     if ($latitude != $latitude2 || $longitude != $longitude2) {
         // The two points are not the same
         $dist = sin($latitude) * sin($latitude2) + cos($latitude) * cos($latitude2) * cos($longitude2 - $longitude);
         // Safety check
         if ($dist > 0) {
             $sqrt = sqrt(1 - $dist * $dist);
             if ($sqrt > 0) {
                 $dist = $EARTH_RADIUS_MILES * (-1 * atan($dist / $sqrt) + M_PI / 2);
             }
         }
     }
     if ($in_kms) {
         $dist = $dist * $miles2kms;
     }
     $this->dist = round($dist, 2);
 }

 /**
  *  Calculate Great Circle distance
  */
 function __construct($latitude, $longitude, $latitude_origin, $longitude_origin)
 {
     $lat1 = $this->deg2rad($latitude_origin);
     $lat2 = $this->deg2rad($latitude);
     $lon1 = $this->deg2rad($longitude_origin);
     $lon2 = $this->deg2rad($longitude);
     $d = 2 * asin(sqrt(pow(sin(($lat1 - $lat2) / 2), 2) + cos($lat1) * cos($lat2) * pow(sin(($lon1 - $lon2) / 2), 2)));
     if ($d <= 1.0E-7) {
         $tc1 = 0;
         // less than 10 cm: going to self
     } elseif ($lat1 > M_PI / 2.0001) {
         $tc1 = M_PI;
         // starting from N pole
     } elseif ($lat1 < -M_PI / 2.0001) {
         $tc1 = 0;
         // starting from S pole
     } else {
         $tc1 = acos((sin($lat2) - sin($lat1) * cos($d)) / (sin($d) * cos($lat1)));
         if (sin($lon2 - $lon1) < 0) {
             $tc1 = 2 * M_PI - $tc1;
         }
     }
     $this->heading = rad2deg($tc1);
     $this->distance = rad2deg($d) * 60 * 1852;
     /* Assumes Earth radius of 6366.71 km */
 }

 /**
  * Calculate the distance between two
  * points using the Great Circle formula.
  *
  * Supply instances of the coordinate class.
  * 
  * http://www.ga.gov.au/earth-monitoring/geodesy/geodetic-techniques/distance-calculation-algorithms.html#circle
  *
  * @param Treffynnon\Navigator\Coordinate $point1
  * @param Treffynnon\Navigator\Coordinate $point2
  * @return float
  */
 public function calculate(N\LatLong $point1, N\LatLong $point2)
 {
     $celestialBody = $this->getCelestialBody();
     $degrees = acos(sin($point1->getLatitude()->get()) * sin($point2->getLatitude()->get()) + cos($point1->getLatitude()->get()) * cos($point2->getLatitude()->get()) * cos($point2->getLongitude()->get() - $point1->getLongitude()->get()));
     $d = $degrees * $celestialBody->volumetricMeanRadius;
     return $d * 1000;
 }

function imagecharx($img, $char, $x0, $y0, $ylist)
{
    global $bk_color, $fg_color;
    $da = @imagecreate(10, 20) or die("Cannot Initialize new GD image stream");
    $background_color = imagecolorallocate($da, $bk_color[0], $bk_color[1], $bk_color[2]);
    $text_color = imagecolorallocate($da, $fg_color[0], $fg_color[1], $fg_color[2]);
    $color = imagecolorallocate($img, $fg_color[0], $fg_color[1], $fg_color[2]);
    $arg = rand(0, 18) / 100.0 * pi();
    imagestring($da, 18, 0, 0, $char, $text_color);
    for ($i = 0; $i < 200; $i++) {
        $y = @floor($i / 10);
        $x = $i % 10;
        $point_color = imagecolorat($da, $x, $y);
        if ($point_color == $text_color) {
            for ($j = 0; $j < 12; $j++) {
                $dx = 0;
                $dy = 0;
                $p = 6;
                for ($s = 0; $s < $p; $s++) {
                    $dx += rand(0, 1000 / $p) / 100;
                    $dy += rand(0, 1000 / $p) / 100;
                }
                $xx = $x * 5 + $dx - 25;
                $yy = $y * 5 + $dy - 50;
                $x1 = cos($arg) * $xx - sin($arg) * $yy + 25;
                $y1 = sin($arg) * $xx + cos($arg) * $yy + 50;
                imagesetpixel($img, $x0 + $x1, $y0 + $y1, $color);
            }
        }
    }
    imagedestroy($da);
}

 public function testDrawing()
 {
     $pdf = new Zend_Pdf();
     // Add new page generated by Zend_Pdf object (page is attached to the specified the document)
     $pdf->pages[] = $page1 = $pdf->newPage('A4');
     // Add new page generated by Zend_Pdf_Page object (page is not attached to the document)
     $pdf->pages[] = $page2 = new Zend_Pdf_Page(Zend_Pdf_Page::SIZE_LETTER_LANDSCAPE);
     // Create new font
     $font = Zend_Pdf_Font::fontWithName(Zend_Pdf_Font::FONT_HELVETICA);
     // Apply font and draw text
     $page1->setFont($font, 36);
     $page1->setFillColor(Zend_Pdf_Color_Html::color('#9999cc'));
     $page1->drawText('Helvetica 36 text string', 60, 500);
     // Use font object for another page
     $page2->setFont($font, 24);
     $page2->drawText('Helvetica 24 text string', 60, 500);
     // Use another font
     $page2->setFont(Zend_Pdf_Font::fontWithName(Zend_Pdf_Font::FONT_TIMES), 32);
     $page2->drawText('Times-Roman 32 text string', 60, 450);
     // Draw rectangle
     $page2->setFillColor(new Zend_Pdf_Color_GrayScale(0.8));
     $page2->setLineColor(new Zend_Pdf_Color_GrayScale(0.2));
     $page2->setLineDashingPattern(array(3, 2, 3, 4), 1.6);
     $page2->drawRectangle(60, 400, 400, 350);
     // Draw circle
     $page2->setLineDashingPattern(Zend_Pdf_Page::LINE_DASHING_SOLID);
     $page2->setFillColor(new Zend_Pdf_Color_Rgb(1, 0, 0));
     $page2->drawCircle(85, 375, 25);
     // Draw sectors
     $page2->drawCircle(200, 375, 25, 2 * M_PI / 3, -M_PI / 6);
     $page2->setFillColor(new Zend_Pdf_Color_Cmyk(1, 0, 0, 0));
     $page2->drawCircle(200, 375, 25, M_PI / 6, 2 * M_PI / 3);
     $page2->setFillColor(new Zend_Pdf_Color_Rgb(1, 1, 0));
     $page2->drawCircle(200, 375, 25, -M_PI / 6, M_PI / 6);
     // Draw ellipse
     $page2->setFillColor(new Zend_Pdf_Color_Rgb(1, 0, 0));
     $page2->drawEllipse(250, 400, 400, 350);
     $page2->setFillColor(new Zend_Pdf_Color_Cmyk(1, 0, 0, 0));
     $page2->drawEllipse(250, 400, 400, 350, M_PI / 6, 2 * M_PI / 3);
     $page2->setFillColor(new Zend_Pdf_Color_Rgb(1, 1, 0));
     $page2->drawEllipse(250, 400, 400, 350, -M_PI / 6, M_PI / 6);
     // Draw and fill polygon
     $page2->setFillColor(new Zend_Pdf_Color_Rgb(1, 0, 1));
     $x = array();
     $y = array();
     for ($count = 0; $count < 8; $count++) {
         $x[] = 140 + 25 * cos(3 * M_PI_4 * $count);
         $y[] = 375 + 25 * sin(3 * M_PI_4 * $count);
     }
     $page2->drawPolygon($x, $y, Zend_Pdf_Page::SHAPE_DRAW_FILL_AND_STROKE, Zend_Pdf_Page::FILL_METHOD_EVEN_ODD);
     // Draw line
     $page2->setLineWidth(0.5);
     $page2->drawLine(60, 375, 400, 375);
     $pdf->save(dirname(__FILE__) . '/_files/output.pdf');
     unset($pdf);
     $pdf1 = Zend_Pdf::load(dirname(__FILE__) . '/_files/output.pdf');
     $this->assertTrue($pdf1 instanceof Zend_Pdf);
     unset($pdf1);
     unlink(dirname(__FILE__) . '/_files/output.pdf');
 }

 /**
  * Get polygon area fast method
  * 
  * @param float[][] $polygon
  * @param float     $a
  * @param float     $f
  *
  * @return float area of given polygon in square meters 
  * @throws Exception
  */
 public static function getArea($polygon, $a = 6378137.0)
 {
     if (!is_array($polygon) || !is_array($polygon[0])) {
         throw new Exception("Array of array of floats expected!");
     }
     if ($polygon[0][0] != $polygon[count($polygon) - 1][0] || $polygon[0][1] != $polygon[count($polygon) - 1][1]) {
         $polygon[] = $polygon[0];
     }
     $total = 0;
     $previous = $polygon[0];
     $cx = 0;
     $cy = 0;
     for ($i = 1; $i < count($polygon); $i++) {
         $cx = $cx + $polygon[$i][1];
         $cy = $cy + $polygon[$i][0];
     }
     $cx = $cx / count($polygon);
     $cy = $cy / count($polygon);
     $xRef = $cx + 1;
     $yRef = $cy + 1;
     for ($i = 1; $i < count($polygon); $i++) {
         $current = $polygon[$i];
         $earthRadians = $a * pi() / 180;
         // convert to cartesian coordinates in meters, note this not very exact
         $x1 = ($previous[1] - $xRef) * $earthRadians * cos($yRef * pi() / 180);
         $y1 = ($previous[0] - $yRef) * $earthRadians;
         $x2 = ($current[1] - $xRef) * $earthRadians * cos($yRef * pi() / 180);
         $y2 = ($current[0] - $yRef) * $earthRadians;
         $total += $x1 * $y2 - $x2 * $y1;
         $previous = $current;
     }
     return 0.5 * abs($total);
 }

 public function renderGraph()
 {
     $this->i['top_heading_height'] = max(self::$c['size']['headers'] + 22 + self::$c['size']['key'], 48);
     $this->i['top_start'] = $this->i['top_heading_height'] + 50;
     $this->update_graph_dimensions($this->i['graph_width'], $this->i['graph_height'] + $this->i['top_start'], true);
     // Do the actual work
     $this->render_graph_init();
     $this->graph_key_height();
     $this->render_graph_key();
     $this->render_graph_heading();
     $data = array(1, 2, 3, 6, 7, 8, 9, 10);
     $center_block_x = round($this->i['graph_width'] / 2);
     $center_block_y = round($this->i['graph_height'] / 2);
     for ($ring = 0, $blocks_per_ring = count($data) <= 5 ? 5 : 4, $ring_size = ceil(count($data) / $blocks_per_ring); $ring < $ring_size; $ring++) {
         $depth = ($ring + 1) * (min($center_block_x, $center_block_y) / ($ring_size + 0.25));
         for ($i = $ring * $blocks_per_ring, $i_size = $i + $blocks_per_ring; $i < $i_size; $i++) {
             $this_degree = 360 / $blocks_per_ring * ($i % $blocks_per_ring + $ring / $ring_size);
             $this_block_x = round($center_block_x + cos(deg2rad($this_degree)) * $depth);
             $this_block_y = round($center_block_y - sin(deg2rad($this_degree)) * $depth);
             $this->svg_dom->draw_svg_line($center_block_x, $center_block_y, $this_block_x, $this_block_y, self::$c['color']['notches'], 2);
             $this->svg_dom->add_element('rect', array('x' => $this_block_x - 20, 'y' => $this_block_y - 20, 'width' => 40, 'height' => 40, 'fill' => self::$c['color']['alert']));
         }
     }
     $this->svg_dom->add_element('rect', array('x' => $center_block_x - 50, 'y' => $center_block_y - 50, 'width' => 100, 'height' => 100, 'fill' => self::$c['color']['alert']));
 }