var EPSLN = 1.0e-10;
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var msfnz = require('../common/msfnz');
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var tsfnz = require('../common/tsfnz');
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var HALF_PI = Math.PI/2;
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var sign = require('../common/sign');
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var adjust_lon = require('../common/adjust_lon');
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var phi2z = require('../common/phi2z');
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exports.init = function() {
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// array of: r_maj,r_min,lat1,lat2,c_lon,c_lat,false_east,false_north
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//double c_lat; /* center latitude */
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//double c_lon; /* center longitude */
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//double lat1; /* first standard parallel */
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//double lat2; /* second standard parallel */
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//double r_maj; /* major axis */
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//double r_min; /* minor axis */
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//double false_east; /* x offset in meters */
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//double false_north; /* y offset in meters */
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if (!this.lat2) {
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this.lat2 = this.lat1;
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} //if lat2 is not defined
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if (!this.k0) {
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this.k0 = 1;
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}
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this.x0 = this.x0 || 0;
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this.y0 = this.y0 || 0;
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// Standard Parallels cannot be equal and on opposite sides of the equator
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if (Math.abs(this.lat1 + this.lat2) < EPSLN) {
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return;
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}
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var temp = this.b / this.a;
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this.e = Math.sqrt(1 - temp * temp);
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var sin1 = Math.sin(this.lat1);
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var cos1 = Math.cos(this.lat1);
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var ms1 = msfnz(this.e, sin1, cos1);
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var ts1 = tsfnz(this.e, this.lat1, sin1);
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var sin2 = Math.sin(this.lat2);
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var cos2 = Math.cos(this.lat2);
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var ms2 = msfnz(this.e, sin2, cos2);
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var ts2 = tsfnz(this.e, this.lat2, sin2);
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var ts0 = tsfnz(this.e, this.lat0, Math.sin(this.lat0));
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if (Math.abs(this.lat1 - this.lat2) > EPSLN) {
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this.ns = Math.log(ms1 / ms2) / Math.log(ts1 / ts2);
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}
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else {
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this.ns = sin1;
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}
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if (isNaN(this.ns)) {
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this.ns = sin1;
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}
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this.f0 = ms1 / (this.ns * Math.pow(ts1, this.ns));
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this.rh = this.a * this.f0 * Math.pow(ts0, this.ns);
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if (!this.title) {
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this.title = "Lambert Conformal Conic";
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}
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};
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// Lambert Conformal conic 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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// singular cases :
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if (Math.abs(2 * Math.abs(lat) - Math.PI) <= EPSLN) {
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lat = sign(lat) * (HALF_PI - 2 * EPSLN);
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}
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var con = Math.abs(Math.abs(lat) - HALF_PI);
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var ts, rh1;
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if (con > EPSLN) {
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ts = tsfnz(this.e, lat, Math.sin(lat));
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rh1 = this.a * this.f0 * Math.pow(ts, this.ns);
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}
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else {
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con = lat * this.ns;
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if (con <= 0) {
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return null;
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}
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rh1 = 0;
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}
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var theta = this.ns * adjust_lon(lon - this.long0);
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p.x = this.k0 * (rh1 * Math.sin(theta)) + this.x0;
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p.y = this.k0 * (this.rh - rh1 * Math.cos(theta)) + this.y0;
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return p;
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};
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// Lambert Conformal Conic 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 rh1, con, ts;
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var lat, lon;
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var x = (p.x - this.x0) / this.k0;
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var y = (this.rh - (p.y - this.y0) / this.k0);
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if (this.ns > 0) {
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rh1 = Math.sqrt(x * x + y * y);
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con = 1;
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}
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else {
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rh1 = -Math.sqrt(x * x + y * y);
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con = -1;
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}
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var theta = 0;
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if (rh1 !== 0) {
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theta = Math.atan2((con * x), (con * y));
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}
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if ((rh1 !== 0) || (this.ns > 0)) {
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con = 1 / this.ns;
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ts = Math.pow((rh1 / (this.a * this.f0)), con);
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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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else {
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lat = -HALF_PI;
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}
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lon = adjust_lon(theta / this.ns + this.long0);
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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 = ["Lambert Tangential Conformal Conic Projection", "Lambert_Conformal_Conic", "Lambert_Conformal_Conic_2SP", "lcc"];
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