init

2026-10-21 19:32:02 -04:00
commit b74d278c8e
96 changed files with 54476 additions and 0 deletions
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+var CartesianCoord = require('./cartesian.js');
+var LegendreFunction = require('../legendre.js');
+
+module.exports = SphericalCoord;
+
+function SphericalCoord(options){
+	this.lambda = options.lambda; // longitude
+	this.phig = options.phig; // geocentric latitude
+	this.r = options.r; // distance from center of ellipsoid
+}
+
+SphericalCoord.prototype.toCartesian = function(){
+	var radphi = this.phig * Math.PI/180;
+	var radlambda = this.lambda * Math.PI/180;
+	return new CartesianCoord({
+		x: this.r * cos(radphi) * cos(radlambda),
+		y: this.r * cos(radphi) * sin(radlambda),
+		z: this.r * sin(radphi)
+	});
+};
+
+SphericalCoord.prototype.toGeodetic = function(ellipsoid){
+	return this.toCartesian().toGeodetic(ellipsoid);
+};
+
+SphericalCoord.prototype.getHarmonicVariables = function(ellipsoid, n_max){
+	var m, n;
+	var cos_lambda = Math.cos(Math.PI/180 * this.lambda);
+	var sin_lambda = Math.sin(Math.PI/180 * this.lambda);
+
+	var cos_mlambda = [1.0, cos_lambda];
+	var sin_mlambda = [0.0, sin_lambda];
+	var relative_radius_power = [
+		(ellipsoid.re/this.r) * (ellipsoid.re/this.r)
+	];
+
+	for(n = 1; n <= n_max; n++){
+		relative_radius_power[n] = relative_radius_power[n-1] * (ellipsoid.re/this.r);
+	}
+	for(m = 2; m <= n_max; m++){
+		cos_mlambda[m] = cos_mlambda[m-1]*cos_lambda - sin_mlambda[m-1]*sin_lambda;
+		sin_mlambda[m] = cos_mlambda[m-1]*sin_lambda + sin_mlambda[m-1]*cos_lambda;
+	}
+
+	return {
+		relative_radius_power: relative_radius_power,
+		cos_mlambda: cos_mlambda,
+		sin_mlambda: sin_mlambda
+	};
+};
+
+SphericalCoord.prototype.getLegendreFunction = function(n_max) {
+	return new LegendreFunction(this, n_max);
+};