1 d3.geo.mercator = function() {

     2   var scale = 500,

     3       translate = [480, 250];

     4 

     5   function mercator(coordinates) {

     6     var x = coordinates[0] / 360,

     7         y = -(Math.log(Math.tan(Math.PI / 4 + coordinates[1] * d3_geo_radians / 2)) / d3_geo_radians) / 360;

     8     return [

     9       scale * x + translate[0],

    10       scale * Math.max(-.5, Math.min(.5, y)) + translate[1]

    11     ];

    12   }

    13 

    14   mercator.invert = function(coordinates) {

    15     var x = (coordinates[0] - translate[0]) / scale,

    16         y = (coordinates[1] - translate[1]) / scale;

    17     return [

    18       360 * x,

    19       2 * Math.atan(Math.exp(-360 * y * d3_geo_radians)) / d3_geo_radians - 90

    20     ];

    21   };

    22 

    23   mercator.scale = function(x) {

    24     if (!arguments.length) return scale;

    25     scale = +x;

    26     return mercator;

    27   };

    28 

    29   mercator.translate = function(x) {

    30     if (!arguments.length) return translate;

    31     translate = [+x[0], +x[1]];

    32     return mercator;

    33   };

    34 

    35   return mercator;

    36 };