proj4/lib/common/pj_mlfn.js

Proj4js is a JavaScript library to transform point coordinates from one coordinate system to another, including datum transformations.

module.exports = function(phi, sphi, cphi, en) {
  cphi *= sphi;
  sphi *= sphi;
  return (en[0] * phi - cphi * (en[1] + sphi * (en[2] + sphi * (en[3] + sphi * en[4]))));
};