var adjust_lon = require('../common/adjust_lon');
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var adjust_lat = require('../common/adjust_lat');
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var pj_enfn = require('../common/pj_enfn');
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var MAX_ITER = 20;
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var pj_mlfn = require('../common/pj_mlfn');
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var pj_inv_mlfn = require('../common/pj_inv_mlfn');
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var HALF_PI = Math.PI/2;
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var EPSLN = 1.0e-10;
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var asinz = require('../common/asinz');
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exports.init = function() {
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/* Place parameters in static storage for common use
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-------------------------------------------------*/
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if (!this.sphere) {
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this.en = pj_enfn(this.es);
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}
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else {
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this.n = 1;
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this.m = 0;
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this.es = 0;
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this.C_y = Math.sqrt((this.m + 1) / this.n);
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this.C_x = this.C_y / (this.m + 1);
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}
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};
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/* Sinusoidal 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 x, y;
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var lon = p.x;
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var lat = p.y;
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/* Forward equations
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-----------------*/
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lon = adjust_lon(lon - this.long0);
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if (this.sphere) {
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if (!this.m) {
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lat = this.n !== 1 ? Math.asin(this.n * Math.sin(lat)) : lat;
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}
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else {
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var k = this.n * Math.sin(lat);
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for (var i = MAX_ITER; i; --i) {
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var V = (this.m * lat + Math.sin(lat) - k) / (this.m + Math.cos(lat));
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lat -= V;
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if (Math.abs(V) < EPSLN) {
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break;
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}
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}
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}
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x = this.a * this.C_x * lon * (this.m + Math.cos(lat));
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y = this.a * this.C_y * lat;
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}
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else {
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var s = Math.sin(lat);
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var c = Math.cos(lat);
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y = this.a * pj_mlfn(lat, s, c, this.en);
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x = this.a * lon * c / Math.sqrt(1 - this.es * s * s);
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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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exports.inverse = function(p) {
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var lat, temp, lon, s;
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p.x -= this.x0;
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lon = p.x / this.a;
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p.y -= this.y0;
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lat = p.y / this.a;
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if (this.sphere) {
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lat /= this.C_y;
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lon = lon / (this.C_x * (this.m + Math.cos(lat)));
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if (this.m) {
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lat = asinz((this.m * lat + Math.sin(lat)) / this.n);
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}
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else if (this.n !== 1) {
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lat = asinz(Math.sin(lat) / this.n);
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}
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lon = adjust_lon(lon + this.long0);
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lat = adjust_lat(lat);
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}
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else {
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lat = pj_inv_mlfn(p.y / this.a, this.es, this.en);
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s = Math.abs(lat);
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if (s < HALF_PI) {
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s = Math.sin(lat);
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temp = this.long0 + p.x * Math.sqrt(1 - this.es * s * s) / (this.a * Math.cos(lat));
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//temp = this.long0 + p.x / (this.a * Math.cos(lat));
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lon = adjust_lon(temp);
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}
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else if ((s - EPSLN) < HALF_PI) {
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lon = this.long0;
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}
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}
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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 = ["Sinusoidal", "sinu"];
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