anchor.diff:  
   === Ellipsoid
   
  +An ellipsoid is a mathematically defined approximation of the earth's surface.
  +
  +An ellipsoid is defined by two parameters:
  +
  +* the semi-major axis _a_ (equatorial radius)
  +* the semi-minor axis _b_ (polar radius)
  +
  +_a_ and _b_ together define the flattening of the ellipsoid _f_:
  +
  +latexmath:[f = \frac{a-b}{a}]
  +
  +NOTE: _phpgeo's_ ellipsoids are defined by _a_ and _1/f_ instead of _a_
  +and _b_. That's not a problem because each third value can be
  +calculated from the other two.
  +
  +_phpgeo_ supports arbitrary ellipsoids. _WGS-84_ is used as default when
  +no other ellipsoid is given. For day-to-day calculations it's not needed
  +to care about ellipsoids in the most cases.
  +
  +It's possible to create an instance of the Ellipsoid class either by
  +specifing a name or by providing the three parameters _name,_ _a_, and _1/f_.
  +
  +[source,php]
  +----
  +use Location\Ellipsoid;
  +
  +$ellipsoid = Ellipsoid::createDefault('WGS-84'); <1>
  +
  +printf(
  +    "%s: a=%f; b=%f; 1/f=%f\n",
  +    $ellipsoid->getName(),
  +    $ellipsoid->getA(),
  +    $ellipsoid->getB(),
  +    $ellipsoid->getF()
  +);
  +
  +$ellipsoid = new Ellipsoid('GRS-80', 6378137, 298.257222); <2>
  +
  +printf(
  +    "%s: a=%f; b=%f; 1/f=%f\n",
  +    $ellipsoid->getName(),
  +    $ellipsoid->getA(),
  +    $ellipsoid->getB(),
  +    $ellipsoid->getF()
  +);
  +----
  +
  +<1> Create ellipsoid instance from one of the default configurations
  +<2> Create custom ellipsoid by providing name, _a_, and _1/f_
  +
  +The code above will produce the output below:
  +
  +----
  +WGS-84: a=6378137.000000; b=6356752.314245; 1/f=298.257224
  +GRS-80: a=6378137.000000; b=6356752.314133; 1/f=298.257222
  +----
  +
   == Calculations
   
   === Distance and Length
  
positive.code: :toclevels: 3
  :source-highlighter: coderay
  :icons: font
  
  == Introduction
  
  
negative.code: _phpgeo_ is best be installed using Composer. Please visit the
  https://getcomposer.org/[Composer website] website for more information.
  
  To install _phpgeo,_ simply "require" it using Composer:
  
      php composer.phar require mjaschen/phpgeo
  
  