updates to geolocation bits

Source/Meadow.Units.Tests/AzimuthTests.cs

@@ -1,9 +1,45 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Xunit;
 
 namespace Meadow.Units.Tests;
 
+public class CompareToTests
+{
+    [Fact]
+    public void CompareToObjectOfSameType()
+    {
+        // find all comparable structs in the assembly
+        var testTypes = typeof(Temperature)
+            .Assembly
+            .GetTypes()
+            .Where(t => t.IsValueType && typeof(IComparable).IsAssignableFrom(t))
+            .ToArray();
+
+        var failCount = 0;
+        var successCount = 0;
+
+        foreach (var t in testTypes)
+        {
+            var testItemA = Activator.CreateInstance(t);
+            var testItemB = Activator.CreateInstance(t);
+
+            try
+            {
+                var shouldbeZero = (testItemA as IComparable).CompareTo(testItemB);
+                Assert.Equal(0, shouldbeZero);
+                successCount++;
+            }
+            catch (Exception ex)
+            {
+                failCount++;
+            }
+        }
+
+        Assert.True(failCount == 0, $"{failCount} out of {failCount + successCount} failed CompareTo(object)");
+    }
+}
 
 public class AzimuthTests
 {

Source/Meadow.Units/GeoLocation.cs

@@ -1,17 +1,16 @@
-using System;
-using System.Diagnostics.Contracts;
-
-namespace Meadow.Units;
+namespace Meadow.Units;
 
 /// <summary>
 /// Represents a location on the surface of an ideal Earth (latitude and longitude)
 /// </summary>
 public record GeoLocation
 {
+    private static Length? _earthRadius;
+
     /// <summary>
     /// Idealized earth radius used for internal calculations
     /// </summary>
-    public Length EarthRadius => new Length(6371.01, Length.UnitType.Kilometers);
+    public static Length EarthRadius => _earthRadius ??= new Length(6371.01, Length.UnitType.Kilometers);
 
     /// <summary>
     /// The latitude portion of the GeoLocation
@@ -25,90 +24,20 @@ public record GeoLocation
     /// <summary>
     /// Creates a GeoLocation instance
     /// </summary>
-    /// <param name="latitude"></param>
-    /// <param name="longitude"></param>
-    public GeoLocation(double latitude, double longitude)
+    public GeoLocation()
     {
-        Latitude = latitude;
-        Longitude = longitude;
-    }
-
-    [Pure]
-    private static double DegreesToRadians(double degrees)
-    {
-        return degrees * Math.PI / 180.0;
-    }
-
-    [Pure]
-    private static double RadiansToDegrees(double radians)
-    {
-        return radians * 180 / Math.PI;
+        Latitude = 0;
+        Longitude = 0;
     }
 
     /// <summary>
-    /// Calculates the distance to another GeoLocation
-    /// </summary>
-    /// <param name="other"></param>
-    /// <returns></returns>
-    [Pure]
-    public Length DistanceTo(GeoLocation other)
-    {
-        var diffLat = DegreesToRadians(other.Latitude - Latitude);
-        var diffLong = DegreesToRadians(other.Longitude - Longitude);
-
-        var a = Math.Sin(diffLat / 2) * Math.Sin(diffLat / 2) +
-                Math.Cos(DegreesToRadians(Latitude)) * Math.Cos(DegreesToRadians(other.Latitude)) *
-                Math.Sin(diffLong / 2) * Math.Sin(diffLong / 2);
-        var c = 2 * Math.Asin(Math.Min(1, Math.Sqrt(a)));
-        var d = EarthRadius * c;
-
-        return d;
-    }
-
-    /// <summary>
-    /// Calculates the bearing to another GeoLocation
-    /// </summary>
-    /// <param name="other"></param>
-    /// <returns></returns>
-    [Pure]
-    public Azimuth BearingTo(GeoLocation other)
-    {
-        var dLon = DegreesToRadians(other.Longitude - Longitude);
-        var dPhi = Math.Log(Math.Tan(DegreesToRadians(other.Latitude) / 2 + Math.PI / 4) / Math.Tan(DegreesToRadians(Latitude) / 2 + Math.PI / 4));
-        if (Math.Abs(dLon) > Math.PI)
-        {
-            dLon = dLon > 0 ? -(2 * Math.PI - dLon) : (2 * Math.PI + dLon);
-        }
-
-        return Azimuth.FromRadians(Math.Atan2(dLon, dPhi));
-    }
-
-    /// <summary>
-    /// Creates a new GeoLocation a given bearing and distance from the current GeoLocation
+    /// Creates a GeoLocation instance
     /// </summary>
-    /// <param name="bearing">Bearing angle to the new location</param>
-    /// <param name="distance">Distance to the new location</param>
-    /// <returns></returns>
-    [Pure]
-    public GeoLocation Move(Azimuth bearing, Length distance) // double initialBearingRadians, double distanceKilometres)
+    /// <param name="latitude">The latitude portion of the GeoLocation</param>
+    /// <param name="longitude">The longitude portion of the GeoLocation</param>
+    public GeoLocation(double latitude, double longitude)
     {
-        var distRatio = distance.Meters / EarthRadius.Meters;
-        var distRatioSine = Math.Sin(distRatio);
-        var distRatioCosine = Math.Cos(distRatio);
-
-        var startLatRad = DegreesToRadians(Latitude);
-        var startLonRad = DegreesToRadians(Longitude);
-
-        var startLatCos = Math.Cos(startLatRad);
-        var startLatSin = Math.Sin(startLatRad);
-
-        var endLatRads = Math.Asin((startLatSin * distRatioCosine) + (startLatCos * distRatioSine * Math.Cos(bearing.Radians)));
-
-        var endLonRads = startLonRad
-                         + Math.Atan2(
-                             Math.Sin(bearing.Radians) * distRatioSine * startLatCos,
-                             distRatioCosine - startLatSin * Math.Sin(endLatRads));
-
-        return new GeoLocation(RadiansToDegrees(endLatRads), RadiansToDegrees(endLonRads));
+        Latitude = latitude;
+        Longitude = longitude;
     }
 }

Source/Meadow.Units/GeoLocationExtensions.cs

@@ -0,0 +1,89 @@
+using System;
+using System.Diagnostics.Contracts;
+
+namespace Meadow.Units;
+
+/// <summary>
+/// Extension methods for the GeoLocation struct
+/// </summary>
+public static class GeoLocationExtensions
+{
+    [Pure]
+    private static double DegreesToRadians(double degrees)
+    {
+        return degrees * Math.PI / 180.0;
+    }
+
+    [Pure]
+    private static double RadiansToDegrees(double radians)
+    {
+        return radians * 180 / Math.PI;
+    }
+
+    /// <summary>
+    /// Calculates the distance to another GeoLocation
+    /// </summary>
+    /// <param name="self">A Geolocation</param>
+    /// <param name="other">A second GeoLocation</param>
+    [Pure]
+    public static Length DistanceTo(this GeoLocation self, GeoLocation other)
+    {
+        var diffLat = DegreesToRadians(other.Latitude - self.Latitude);
+        var diffLong = DegreesToRadians(other.Longitude - self.Longitude);
+
+        var a = Math.Sin(diffLat / 2) * Math.Sin(diffLat / 2) +
+                Math.Cos(DegreesToRadians(self.Latitude)) * Math.Cos(DegreesToRadians(other.Latitude)) *
+                Math.Sin(diffLong / 2) * Math.Sin(diffLong / 2);
+        var c = 2 * Math.Asin(Math.Min(1, Math.Sqrt(a)));
+        var d = GeoLocation.EarthRadius * c;
+
+        return d;
+    }
+
+    /// <summary>
+    /// Calculates the bearing to another GeoLocation
+    /// </summary>
+    /// <param name="self">A Geolocation</param>
+    /// <param name="other">A second GeoLocation</param>
+    [Pure]
+    public static Azimuth BearingTo(this GeoLocation self, GeoLocation other)
+    {
+        var dLon = DegreesToRadians(other.Longitude - self.Longitude);
+        var dPhi = Math.Log(Math.Tan(DegreesToRadians(other.Latitude) / 2 + Math.PI / 4) / Math.Tan(DegreesToRadians(self.Latitude) / 2 + Math.PI / 4));
+        if (Math.Abs(dLon) > Math.PI)
+        {
+            dLon = dLon > 0 ? -(2 * Math.PI - dLon) : (2 * Math.PI + dLon);
+        }
+
+        return Azimuth.FromRadians(Math.Atan2(dLon, dPhi));
+    }
+
+    /// <summary>
+    /// Creates a new GeoLocation a given bearing and distance from the current GeoLocation
+    /// </summary>
+    /// <param name="self">A Geolocation</param>
+    /// <param name="bearing">Bearing angle to the new location</param>
+    /// <param name="distance">Distance to the new location</param>
+    [Pure]
+    public static GeoLocation Move(this GeoLocation self, Azimuth bearing, Length distance) // double initialBearingRadians, double distanceKilometres)
+    {
+        var distRatio = distance.Meters / GeoLocation.EarthRadius.Meters;
+        var distRatioSine = Math.Sin(distRatio);
+        var distRatioCosine = Math.Cos(distRatio);
+
+        var startLatRad = DegreesToRadians(self.Latitude);
+        var startLonRad = DegreesToRadians(self.Longitude);
+
+        var startLatCos = Math.Cos(startLatRad);
+        var startLatSin = Math.Sin(startLatRad);
+
+        var endLatRads = Math.Asin((startLatSin * distRatioCosine) + (startLatCos * distRatioSine * Math.Cos(bearing.Radians)));
+
+        var endLonRads = startLonRad
+                         + Math.Atan2(
+                             Math.Sin(bearing.Radians) * distRatioSine * startLatCos,
+                             distRatioCosine - startLatSin * Math.Sin(endLatRads));
+
+        return new GeoLocation(RadiansToDegrees(endLatRads), RadiansToDegrees(endLonRads));
+    }
+}

Source/Meadow.Units/GeographicCoordinate.cs

@@ -0,0 +1,12 @@
+namespace Meadow.Units;
+
+/// <summary>
+/// A geographic 
+/// </summary>
+public record GeographicCoordinate : GeoLocation
+{
+    /// <summary>
+    /// The altitude portion of the GeographicCoordinate
+    /// </summary>
+    public Length Altitude { get; set; }
+}