aeqd.js
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Proj4js.Proj.aeqd = {
init : function() {
this.sin_p12=Math.sin(this.lat0);
this.cos_p12=Math.cos(this.lat0);
},
forward: function(p) {
var lon=p.x;
var lat=p.y;
var ksp;
var sinphi=Math.sin(p.y);
var cosphi=Math.cos(p.y);
var dlon = Proj4js.common.adjust_lon(lon - this.long0);
var coslon = Math.cos(dlon);
var g = this.sin_p12 * sinphi + this.cos_p12 * cosphi * coslon;
if (Math.abs(Math.abs(g) - 1.0) < Proj4js.common.EPSLN) {
ksp = 1.0;
if (g < 0.0) {
Proj4js.reportError("aeqd:Fwd:PointError");
return;
}
} else {
var z = Math.acos(g);
ksp = z/Math.sin(z);
}
p.x = this.x0 + this.a * ksp * cosphi * Math.sin(dlon);
p.y = this.y0 + this.a * ksp * (this.cos_p12 * sinphi - this.sin_p12 * cosphi * coslon);
return p;
},
inverse: function(p){
p.x -= this.x0;
p.y -= this.y0;
var rh = Math.sqrt(p.x * p.x + p.y *p.y);
if (rh > (2.0 * Proj4js.common.HALF_PI * this.a)) {
Proj4js.reportError("aeqdInvDataError");
return;
}
var z = rh / this.a;
var sinz=Math.sin(z);
var cosz=Math.cos(z);
var lon = this.long0;
var lat;
if (Math.abs(rh) <= Proj4js.common.EPSLN) {
lat = this.lat0;
} else {
lat = Proj4js.common.asinz(cosz * this.sin_p12 + (p.y * sinz * this.cos_p12) / rh);
var con = Math.abs(this.lat0) - Proj4js.common.HALF_PI;
if (Math.abs(con) <= Proj4js.common.EPSLN) {
if (lat0 >= 0.0) {
lon = Proj4js.common.adjust_lon(this.long0 + Math.atan2(p.x , -p.y));
} else {
lon = Proj4js.common.adjust_lon(this.long0 - Math.atan2(-p.x , p.y));
}
} else {
con = cosz - this.sin_p12 * Math.sin(lat);
if ((Math.abs(con) < Proj4js.common.EPSLN) && (Math.abs(p.x) < Proj4js.common.EPSLN)) {
//no-op, just keep the lon value as is
} else {
var temp = Math.atan2((p.x * sinz * this.cos_p12), (con * rh));
lon = Proj4js.common.adjust_lon(this.long0 + Math.atan2((p.x * sinz * this.cos_p12), (con * rh)));
}
}
}
p.x = lon;
p.y = lat;
return p;
}
};