lune - npm Package Compare versions

Comparing version 0.2.0 to 0.2.1

lib/lune.js

@@ -12,4 +12,7 @@ /**
 (function() {
+  "use strict";
+
+  var julian = require("./julian");
+
   // Phases of the moon & precision
-
   var PRECISION = 0.05;
@@ -22,111 +25,59 @@ var NEW = 0 / 4.0;
 
-  /**
-   * Gets the Julian value from a date object.
-   * Source: http://javascript.about.com/library/bljulday.htm
-   * @return {Number} Julian number representation of the date.
-   */
-  Date.prototype.getJulian = function() {
-    return (this.valueOf() / 86400000) - (this.getTimezoneOffset() / 1440) + 2440587.5;
-  };
+  // Astronomical Constants
+  // JDN stands for Julian Day Number
+  // Angles here are in degrees
 
-  /**
-   * Converts a Number in Julian date form to a Date object.
-   * Source: http://blog.bahrenburgs.com/2011/01/javascript-julian-day-conversions.html
-   */
-  Number.prototype.Julian2Date = function(inUTC) {
-    var X = parseFloat(this)+0.5;
-    var Z = Math.floor(X); //Get day without time
-    var F = X - Z; //Get time
-    var Y = Math.floor((Z-1867216.25)/36524.25);
-    var A = Z+1+Y-Math.floor(Y/4);
-    var B = A+1524;
-    var C = Math.floor((B-122.1)/365.25);
-    var D = Math.floor(365.25*C);
-    var G = Math.floor((B-D)/30.6001);
-    //must get number less than or equal to 12)
-    var month = (G<13.5) ? (G-1) : (G-13);
-    //if Month is January or February, or the rest of year
-    var year = (month<2.5) ? (C-4715) : (C-4716);
-    month -= 1; //Handle JavaScript month format
-    var UT = B-D-Math.floor(30.6001*G)+F;
-    var day = Math.floor(UT);
-    //Determine time
-    UT -= Math.floor(UT);
-    UT *= 24;
-    var hour = Math.floor(UT);
-    UT -= Math.floor(UT);
-    UT *= 60;
-    var minute = Math.floor(UT);
-    UT -= Math.floor(UT);
-    UT *= 60;
-    var second = Math.round(UT);
+  // 1980 January 0.0 in JDN
+  // XXX: DateTime(1980).jdn yields 2444239.5 -- which one is right?
+  var EPOCH = 2444238.5;
 
-    if (inUTC) {
-      return new Date(Date.UTC(year, month, day, hour, minute, second));
-    } else {
-      return new Date(year, month, day, hour, minute, second);
-    }
-  };
+  // Ecliptic longitude of the Sun at epoch 1980.0
+  var ECLIPTIC_LONGITUDE_EPOCH = 278.833540;
 
-  /**
-   * Astronomical Constants
-   * @type {Object}
-   */
-  const c = {
-    // JDN stands for Julian Day Number
-    // Angles here are in degrees
+  // Ecliptic longitude of the Sun at perigee
+  var ECLIPTIC_LONGITUDE_PERIGEE = 282.596403;
 
-    // 1980 January 0.0 in JDN
-    // XXX: DateTime(1980).jdn yields 2444239.5 -- which one is right?
-    epoch: 2444238.5,
+  // Eccentricity of Earth's orbit
+  var ECCENTRICITY = 0.016718;
 
-    // Ecliptic longitude of the Sun at epoch 1980.0
-    ecliptic_longitude_epoch: 278.833540,
+  // Semi-major axis of Earth's orbit, in kilometers
+  var SUN_SMAXIS = 1.49585e8;
 
-    // Ecliptic longitude of the Sun at perigee
-    ecliptic_longitude_perigee: 282.596403,
+  // Sun's angular size, in degrees, at semi-major axis distance
+  var SUN_ANGULAR_SIZE_SMAXIS = 0.533128;
 
-    // Eccentricity of Earth's orbit
-    eccentricity: 0.016718,
+  // Elements of the Moon's orbit, epoch 1980.0
+  // Moon's mean longitude at the epoch
+  var MOON_MEAN_LONGITUDE_EPOCH = 64.975464;
 
-    // Semi-major axis of Earth's orbit, in kilometers
-    sun_smaxis: 1.49585e8,
+  // Mean longitude of the perigee at the epoch
+  var MOON_MEAN_PERIGEE_EPOCH = 349.383063;
 
-    // Sun's angular size, in degrees, at semi-major axis distance
-    sun_angular_size_smaxis: 0.533128,
+  // Mean longitude of the node at the epoch
+  var NODE_MEAN_LONGITUDE_EPOCH = 151.950429;
 
-    // Elements of the Moon's orbit, epoch 1980.0
+  // Inclination of the Moon's orbit
+  var MOON_INCLINATION = 5.145396;
 
-    // Moon's mean longitude at the epoch
-    moon_mean_longitude_epoch: 64.975464,
-    // Mean longitude of the perigee at the epoch
-    moon_mean_perigee_epoch: 349.383063,
+  // Eccentricity of the Moon's orbit
+  var MOON_ECCENTRICITY = 0.054900;
 
-    // Mean longitude of the node at the epoch
-    node_mean_longitude_epoch: 151.950429,
+  // Moon's angular size at distance a from Earth
+  var MOON_ANGULAR_SIZE = 0.5181;
 
-    // Inclination of the Moon's orbit
-    moon_inclination: 5.145396,
+  // Semi-mojor axis of the Moon's orbit, in kilometers
+  var MOON_SMAXIS = 384401.0;
 
-    // Eccentricity of the Moon's orbit
-    moon_eccentricity: 0.054900,
+  // Parallax at a distance a from Earth
+  var MOON_PARALLAX = 0.9507;
 
-    // Moon's angular size at distance a from Earth
-    moon_angular_size: 0.5181,
+  // Synodic month (new Moon to new Moon), in days
+  var SYNODIC_MONTH = 29.53058868;
 
-    // Semi-mojor axis of the Moon's orbit, in kilometers
-    moon_smaxis: 384401.0,
-    // Parallax at a distance a from Earth
-    moon_parallax: 0.9507,
+  // Base date for E. W. Brown's numbered series of lunations (1923 January 16)
+  var LUNATIONS_BASE = 2423436.0;
 
-    // Synodic month (new Moon to new Moon), in days
-    synodic_month: 29.53058868,
+  // Properties of the Earth
+  var EARTH_RADIUS = 6378.16;
 
-    // Base date for E. W. Brown's numbered series of lunations (1923 January 16)
-    lunations_base: 2423436.0,
-
-    // #Properties of the Earth
-    earth_radius: 6378.16
-  };
-
   function fixangle(a) {
@@ -189,9 +140,7 @@ return a - 360.0 * Math.floor(a/360.0);
     if(!phase_date) {
-      phase_date = (new Date()).getJulian();
+      phase_date = new Date();
     }
-    else {
-      phase_date = phase_date.getJulian();
-    }
+    phase_date = julian.fromDate(phase_date);
 
-    var day = phase_date - c.epoch;
+    var day = phase_date - EPOCH;
 
@@ -201,18 +150,18 @@ // Mean anomaly of the Sun
     //Convert from perigee coordinates to epoch 1980
-    var M = fixangle(N + c.ecliptic_longitude_epoch - c.ecliptic_longitude_perigee);
+    var M = fixangle(N + ECLIPTIC_LONGITUDE_EPOCH - ECLIPTIC_LONGITUDE_PERIGEE);
 
     // Solve Kepler's equation
-    var Ec = kepler(M, c.eccentricity);
-    Ec = Math.sqrt((1 + c.eccentricity) / (1 - c.eccentricity)) * Math.tan(Ec/2.0);
+    var Ec = kepler(M, ECCENTRICITY);
+    Ec = Math.sqrt((1 + ECCENTRICITY) / (1 - ECCENTRICITY)) * Math.tan(Ec / 2);
     // True anomaly
     Ec = 2 * todeg(Math.atan(Ec));
     // Suns's geometric ecliptic longuitude
-    var lambda_sun = fixangle(Ec + c.ecliptic_longitude_perigee);
+    var lambda_sun = fixangle(Ec + ECLIPTIC_LONGITUDE_PERIGEE);
 
     // Orbital distance factor
-    var F = ((1 + c.eccentricity * Math.cos(torad(Ec))) / (1 - Math.pow(c.eccentricity, 2)));
+    var F = ((1 + ECCENTRICITY * Math.cos(torad(Ec))) / (1 - ECCENTRICITY * ECCENTRICITY));
 
     // Distance to Sun in km
-    var sun_dist = c.sun_smaxis / F;
-    var sun_angular_diameter = F * c.sun_angular_size_smaxis;
+    var sun_dist = SUN_SMAXIS / F;
+    var sun_angular_diameter = F * SUN_ANGULAR_SIZE_SMAXIS;
 
@@ -222,9 +171,9 @@ // Calculation of the Moon's position
     // Moon's mean longitude
-    var moon_longitude = fixangle(13.1763966 * day + c.moon_mean_longitude_epoch);
+    var moon_longitude = fixangle(13.1763966 * day + MOON_MEAN_LONGITUDE_EPOCH);
 
     // Moon's mean anomaly
-    var MM = fixangle(moon_longitude - 0.1114041 * day - c.moon_mean_perigee_epoch);
+    var MM = fixangle(moon_longitude - 0.1114041 * day - MOON_MEAN_PERIGEE_EPOCH);
 
     // Moon's ascending node mean longitude
-    // MN = fixangle(c.node_mean_longitude_epoch - 0.0529539 * day)
+    // MN = fixangle(NODE_MEAN_LONGITUDE_EPOCH - 0.0529539 * day)
 
@@ -265,22 +214,20 @@ var evection = 1.2739 * Math.sin(torad(2*(moon_longitude - lambda_sun) - MM));
     // Calculate distance of Moon from the centre of the Earth
-    var moon_dist = (c.moon_smaxis * (1 - Math.pow(c.moon_eccentricity,2))) / (1 + c.moon_eccentricity * Math.cos(torad(MmP + mEc)));
+    var moon_dist = (MOON_SMAXIS * (1 - MOON_ECCENTRICITY * MOON_ECCENTRICITY)) / (1 + MOON_ECCENTRICITY * Math.cos(torad(MmP + mEc)));
 
     // Calculate Moon's angular diameter
-    var moon_diam_frac = moon_dist / c.moon_smaxis;
-    var moon_angular_diameter = c.moon_angular_size / moon_diam_frac;
+    var moon_diam_frac = moon_dist / MOON_SMAXIS;
+    var moon_angular_diameter = MOON_ANGULAR_SIZE / moon_diam_frac;
 
     // Calculate Moon's parallax (unused?)
-    // moon_parallax = c.moon_parallax / moon_diam_frac
+    // moon_parallax = MOON_PARALLAX / moon_diam_frac
 
-    var res = {
-      'phase': fixangle(moon_age) / 360.0,
-      'illuminated': moon_phase,
-      'age': c.synodic_month * fixangle(moon_age) / 360.0,
-      'distance': moon_dist,
-      'angular_diameter': moon_angular_diameter,
-      'sun_distance': sun_dist,
-      'sun_angular_diameter': sun_angular_diameter
+    return {
+      phase: fixangle(moon_age) / 360.0,
+      illuminated: moon_phase,
+      age: SYNODIC_MONTH * fixangle(moon_age) / 360.0,
+      distance: moon_dist,
+      angular_diameter: moon_angular_diameter,
+      sun_distance: sun_dist,
+      sun_angular_diameter: sun_angular_diameter
     };
-
-    return res;
   }
@@ -300,3 +247,3 @@
 
-    var adate = new Date(sdate.valueOf()); // today!
+    var adate = new Date(sdate.getTime()); // today!
     var x = 45; // go back 45 days!
@@ -309,6 +256,6 @@ adate.setDate(adate.getDate() - x);
 
-    sdate = sdate.getJulian();
+    sdate = julian.fromDate(sdate);
     var k2;
     while(1) {
-      adate = adate + c.synodic_month;
+      adate = adate + SYNODIC_MONTH;
       k2 = k1 + 1;
@@ -356,3 +303,3 @@ var nt2 = meanphase(adate, k2);
     var pt = (
-      2415020.75933 + c.synodic_month * k + 0.0001178 * t2 -
+      2415020.75933 + SYNODIC_MONTH * k + 0.0001178 * t2 -
       0.000000155 * t3 + 0.00033 * dsin(166.56 + 132.87 * t -
@@ -425,3 +372,3 @@ 0.009173 * t2)
 
-    return pt.Julian2Date(true);
+    return julian.toDate(pt);
   }
@@ -441,4 +388,4 @@
 
-    // Time in Julian centuries from 1900 January 12 noon
-    var delta_t = (sdate - (new Date(1900,0,1,12))) / (1000*60*60*24);
+    // Time in Julian centuries from 1900 January 12 noon UTC
+    var delta_t = (sdate - (-2208945600000)) / (1000*60*60*24);
     var t = delta_t / 36525;
@@ -451,4 +398,4 @@
 
-    nt1 = (
-      2415020.75933 + c.synodic_month * k + 0.0001178 * t2 -
+    var nt1 = (
+      2415020.75933 + SYNODIC_MONTH * k + 0.0001178 * t2 -
       0.000000155 * t3 + 0.00033 * dsin(166.56 + 132.87 * t -
@@ -461,6 +408,4 @@ 0.009173 * t2)
 
-  module.exports = {
-   'phase_hunt': phase_hunt,
-   'phase': phase
-  };
+  exports.phase = phase;
+  exports.phase_hunt = phase_hunt;
 })();

package.json

 {
   "name": "lune",
-  "version": "0.2.0",
+  "version": "0.2.1",
   "description": "Calculate the phases of the moon",
@@ -21,7 +21,7 @@ "keywords": [
   },
-  "main": "index.js",
+  "main": "lib/lune.js",
   "license": "Apache-2.0",
   "devDependencies": {
-    "assert": "~1.1.1",
-    "mocha": "~1.17.1"
+    "chai": "~3.5.0",
+    "mocha": "~2.4.5"
   },
@@ -28,0 +28,0 @@ "scripts": {

README.md

@@ -5,3 +5,3 @@ <div align="center">
 
-# Lune [![Build Status](https://travis-ci.org/ryanseys/lune.png)](https://travis-ci.org/ryanseys/lune)
+# Lune [![Build Status](https://travis-ci.org/ryanseys/lune.svg?branch=0.2.0)](https://travis-ci.org/ryanseys/lune)
 
@@ -12,3 +12,5 @@ Lune.js — calculate the phases of the moon.
 
-`npm install lune`
+```sh   
+npm install lune
+```
 
@@ -15,0 +17,0 @@ ## Usage

test/index.js

@@ -1,40 +0,113 @@
-var assert = require("assert");
-var lune = require('../lib/lune');
+var assert = require("chai").assert;
+var lune = require("../lib/lune");
+var julian = require("../lib/julian");
 
-describe('lune', function() {
-  describe('#phase()', function() {
-    it('should return expected values for feb 17th data', function() {
+describe("lune", function() {
+  describe("#phase()", function() {
+    it("should return expected values for Feb 17th data", function() {
+      var phase = lune.phase(new Date("2014-02-17T00:00-0500"));
 
-      var feb17 = {
-        phase: 0.5616632223402672,
-        illuminated: 0.9629393807872504,
-        age: 16.586245595613818,
-        distance: 396868.3763643785,
-        angular_diameter: 0.5018242066159135,
-        sun_distance: 147816061.66410872,
-        sun_angular_diameter: 0.5395080276270386
-      };
+      assert.closeTo(phase.phase,                    0.568 ,      0.001 );
+      assert.closeTo(phase.illuminated,              0.955 ,      0.001 );
+      assert.closeTo(phase.age,                     16.779 ,      0.030 );
+      assert.closeTo(phase.distance,            396084.5   ,    384.4   );
+      assert.closeTo(phase.angular_diameter,         0.5028,      0.0005);
+      assert.closeTo(phase.sun_distance,     147822500     , 149600     );
+      assert.closeTo(phase.sun_angular_diameter,     0.5395,      0.0005);
+    });
 
-      var lunedata = lune.phase(new Date(2014, 1, 17));
+    // http://bazaar.launchpad.net/~keturn/py-moon-phase/trunk/view/head:/moontest.py
+    it("should be accurate to astronomical observations", function() {
+      var observations = [
+            ["1989-01-07T19:22Z", 0.00],
+            ["1989-01-14T13:58Z", 0.25],
+            ["1989-01-21T21:33Z", 0.50],
+            ["1989-01-30T02:02Z", 0.75],
+            ["1989-02-06T07:37Z", 0.00],
+            ["1989-02-12T23:15Z", 0.25],
+            ["1989-02-20T15:32Z", 0.50],
+            ["1989-02-28T20:08Z", 0.75],
+            ["1989-03-07T18:19Z", 0.00],
+            ["1989-03-14T10:11Z", 0.25],
+            ["1989-03-22T09:58Z", 0.50],
+            ["1989-03-30T10:21Z", 0.75],
+            ["1989-04-06T03:33Z", 0.00],
+            ["1989-04-12T23:13Z", 0.25],
+            ["1989-04-21T03:13Z", 0.50],
+            ["1989-04-28T20:46Z", 0.75],
+            ["1989-05-05T11:46Z", 0.00],
+            ["1989-05-12T14:19Z", 0.25],
+            ["1989-05-20T18:16Z", 0.50],
+            ["1989-05-28T04:01Z", 0.75],
+            ["1989-06-03T19:53Z", 0.00],
+            ["1989-06-11T06:59Z", 0.25],
+            ["1989-06-19T06:57Z", 0.50],
+            ["1989-06-26T09:09Z", 0.75],
+            ["1989-07-03T04:59Z", 0.00],
+            ["1989-07-11T00:19Z", 0.25],
+            ["1989-07-18T17:42Z", 0.50],
+            ["1989-07-25T13:31Z", 0.75],
+            ["1989-08-01T16:06Z", 0.00],
+            ["1989-08-09T17:28Z", 0.25],
+            ["1989-08-17T03:07Z", 0.50],
+            ["1989-08-23T18:40Z", 0.75],
+            ["1989-08-31T05:44Z", 0.00],
+            ["1989-09-08T09:49Z", 0.25],
+            ["1989-09-15T11:51Z", 0.50],
+            ["1989-09-22T02:10Z", 0.75],
+            ["1989-09-29T21:47Z", 0.00]
+          ];
 
-      assert.equal(JSON.stringify(feb17), JSON.stringify(lunedata));
+      var error = 0;
+      var i;
+      var obs;
+      var e;
+      for(i = 0; i < observations.length; i++) {
+        obs = observations[i];
+        e = Math.abs(lune.phase(new Date(obs[0])).phase - obs[1]);
+        if(e > 0.5) {
+          // phase is circular
+          e = 1 - e;
+        }
+        error += e;
+      }
+      assert.isAtMost(error / observations.length, 0.001);
     });
   });
 
-    describe('#phase_hunt', function() {
-        it('should handle timezones correctly', function() {
-            process.env.TZ = 'America/New_York';
-            var d = new Date(2014, 10, 1, 16, 56, 00);
-            var t = d.getTime();
-            if (1414837560000 != t) {
-                console.log('Unable to run timezone test because process.env.TZ quirk. '+
-                            'See https://github.com/joyent/node/issues/3286');
-                return;
-            }
-            var hunt = lune.phase_hunt(d);
-            // 1415292777000 incorrect EST time
-            // 1415312577000 correct UTC time
-            assert(1415312577000, hunt.full_date.getTime());
-        });
+  describe("#phase_hunt", function() {
+    it("should handle timezones correctly", function() {
+      var d = new Date("2014-11-01T06:26-0400");
+      var hunt = lune.phase_hunt(d);
+      // 1415292777000 incorrect EST time
+      // 1415312577000 correct UTC time
+      // date conversion is now accurate to the millisecond, but these tests
+      // were written when they were only accurate to the second
+      assert.closeTo(hunt.full_date.getTime(), 1415312577000, 500);
     });
+  });
 });
+
+describe("julian", function() {
+  describe("#fromDate", function() {
+    /* http://aa.usno.navy.mil/data/docs/JulianDate.php */
+    it("should convert 2000-01-01T00:00Z to 2451544.5", function() {
+      assert.closeTo(
+        julian.fromDate(new Date("2000-01-01T00:00Z")),
+        2451544.5,
+        0.5/86400
+      );
+    });
+  });
+
+  describe("#toDate", function() {
+    /* http://aa.usno.navy.mil/data/docs/JulianDate.php */
+    it("should convert 2457464.179862 to 2016-03-16T16:19Z", function() {
+      assert.closeTo(
+        julian.toDate(2457464.179862).getTime(),
+        (new Date("2016-03-16T16:19Z")).getTime(),
+        500
+      );
+    });
+  });
+});

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increased by4.54%

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increased by14.29%

Lines of code

434

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Number of lines in readme file

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