attempt at robust-split for robust geometric predicates

robust-split.js

var SPLITTER = +(Math.pow(2, 27) + 1.0)
var rsplit = function(a) {
  var ret = new Array(2);
  var c = SPLITTER*a
  
  ret[1] = c - (c - a);
  ret[0] = a - ret[1];
  
  return ret;
}

console.log(rsplit(.3));
// output: [2.980232227667301e-9, 0.29999999701976776]
// vs
// robust-sum([.1], [.2]) === [-2.7755575615628914e-17, 0.30000000000000004]
// twoSum(.2, .1).toString() === robustSum([.2], [.1]).toString()