var msfnz = require('../common/msfnz');
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var HALF_PI = Math.PI/2;
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var EPSLN = 1.0e-10;
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var R2D = 57.29577951308232088;
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var adjust_lon = require('../common/adjust_lon');
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var FORTPI = Math.PI/4;
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var tsfnz = require('../common/tsfnz');
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var phi2z = require('../common/phi2z');
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exports.init = function() {
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var con = this.b / this.a;
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this.es = 1 - con * con;
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if(!('x0' in this)){
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this.x0 = 0;
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}
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if(!('y0' in this)){
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this.y0 = 0;
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}
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this.e = Math.sqrt(this.es);
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if (this.lat_ts) {
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if (this.sphere) {
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this.k0 = Math.cos(this.lat_ts);
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}
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else {
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this.k0 = msfnz(this.e, Math.sin(this.lat_ts), Math.cos(this.lat_ts));
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}
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}
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else {
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if (!this.k0) {
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if (this.k) {
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this.k0 = this.k;
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}
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else {
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this.k0 = 1;
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}
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}
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}
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};
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/* Mercator forward equations--mapping lat,long to x,y
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--------------------------------------------------*/
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exports.forward = function(p) {
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var lon = p.x;
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var lat = p.y;
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// convert to radians
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if (lat * R2D > 90 && lat * R2D < -90 && lon * R2D > 180 && lon * R2D < -180) {
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return null;
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}
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var x, y;
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if (Math.abs(Math.abs(lat) - HALF_PI) <= EPSLN) {
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return null;
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}
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else {
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if (this.sphere) {
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x = this.x0 + this.a * this.k0 * adjust_lon(lon - this.long0);
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y = this.y0 + this.a * this.k0 * Math.log(Math.tan(FORTPI + 0.5 * lat));
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}
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else {
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var sinphi = Math.sin(lat);
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var ts = tsfnz(this.e, lat, sinphi);
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x = this.x0 + this.a * this.k0 * adjust_lon(lon - this.long0);
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y = this.y0 - this.a * this.k0 * Math.log(ts);
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}
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p.x = x;
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p.y = y;
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return p;
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}
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};
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/* Mercator inverse equations--mapping x,y to lat/long
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--------------------------------------------------*/
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exports.inverse = function(p) {
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var x = p.x - this.x0;
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var y = p.y - this.y0;
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var lon, lat;
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if (this.sphere) {
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lat = HALF_PI - 2 * Math.atan(Math.exp(-y / (this.a * this.k0)));
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}
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else {
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var ts = Math.exp(-y / (this.a * this.k0));
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lat = phi2z(this.e, ts);
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if (lat === -9999) {
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return null;
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}
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}
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lon = adjust_lon(this.long0 + x / (this.a * this.k0));
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p.x = lon;
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p.y = lat;
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return p;
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};
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exports.names = ["Mercator", "Popular Visualisation Pseudo Mercator", "Mercator_1SP", "Mercator_Auxiliary_Sphere", "merc"];
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