Mostly done with readme

natemcintosh · Aug 28, 2022 · d78776c · d78776c
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diff --git a/README.md b/README.md
@@ -13,7 +13,6 @@ A golang port of [geographiclib](https://geographiclib.sourceforge.io/).
 - [Short Explanation](#short-explanation-of-library)
 - [Long Explanation](#long-explanation-of-library)
 - [Library Interface](#the-library-interface)
-- [GeographicLib API](#geographiclib-api)
 - [Examples](#examples)
 - [Progress](#progress)
 
@@ -145,14 +144,73 @@ Reasonably accurate results can be obtained for $−0.2 \le f \le 0.2$. Here is
 
 Here 1 nm = 1 nanometer = $10^{−9}$ m (not 1 nautical mile!)
 
-## GeographicLib API
-
 ## Examples
-- [ ] Add Examples to README
-    - [ ] Examples of direct case on Earth
-    - [ ] Examples of direct case on Mars
-    - [ ] Examples of inverse case
-    - [ ] Examples of calculating an area
+```go
+package geographiclibgo_test
+
+import (
+	"fmt"
+
+	geodesic "github.com/natemcintosh/geographiclib-go"
+)
+
+func Example() {
+	// Create a struct representing the Earth
+	earth := geodesic.Wgs84()
+
+	// If I start in the middle of Times Square in New York City, and head due West for
+	// 1000km, where will I end up?
+	NY_lat := 40.757954
+	NY_lon := -73.985548
+	ended_up_at := earth.DirectCalcLatLon(NY_lat, NY_lon, -90, 1000e3)
+	fmt.Println("Ended up at", ended_up_at)
+
+	// Looking on a map, we have ended up in Lafayette Township, a little ways outside
+	// Indianapolis
+
+	// Now let's do the inverse calculation. What is the distance from New York City to
+	// Chicago?
+	CHI_lat := 41.882609
+	CHI_lon := -87.621978
+	NYC_to_CHI_dist := earth.InverseCalcDistance(NY_lat, NY_lon, CHI_lat, CHI_lon)
+	fmt.Printf("Distance from NYC to CHI is %0.1f m\n", NYC_to_CHI_dist)
+
+	// Wyoming is a fairly rectangular state. Taking its four corners as its boundaries,
+	// what is its area?
+	WY_corners_lat_lon := [][2]float64{
+		{40.997958, -111.046710},
+		{45.001311, -111.055200},
+		{44.997380, -104.057699},
+		{41.001432, -104.053249},
+	}
+	polygon := geodesic.NewPolygonArea(earth, false)
+	for _, corner := range WY_corners_lat_lon {
+		polygon.AddPoint(corner[0], corner[1])
+	}
+	polygon_result := polygon.Compute(true, false)
+	fmt.Printf("Wyoming area is approximatley %0.0f m^2\n", polygon_result.Area)
+
+	// What is the approximate perimeter of Wyoming?
+	fmt.Printf("Wyoming perimeter is approximately %0.0f m\n", polygon_result.Perimeter)
+
+	// But we don't only have to do calculations on Earth. Let's try some on Mars!
+	mars_equatorial_radius_m := 3396.2e3
+	mars_flattening_factor := 5.0304e-3
+	mars := geodesic.NewGeodesic(mars_equatorial_radius_m, mars_flattening_factor)
+
+	// What is the distance from Olympus Mons (18.65, -133.8) to the Curiosity Rover's
+	// landing site (-4.47, 137.42)?
+	mars_distance := mars.InverseCalcDistance(18.65, -133.8, -4.47, 137.42)
+	fmt.Printf("Olympus Mons to Curiosity landing site is %0.0f m", mars_distance)
+
+	// Output:
+	// Ended up at {40.15431701948773 -85.75720579845405}
+	// Distance from NYC to CHI is 1147311.9 m
+	// Wyoming area is approximatley 253282066939 m^2
+	// Wyoming perimeter is approximately 2028472 m
+	// Olympus Mons to Curiosity landing site is 5348380 m
+}
+```
 
 
 ## Progress

diff --git a/example_test.go b/example_test.go
@@ -0,0 +1,64 @@
+package geographiclibgo_test
+
+import (
+	"fmt"
+
+	geodesic "github.com/natemcintosh/geographiclib-go"
+)
+
+func Example() {
+	// Create a struct representing the Earth
+	earth := geodesic.Wgs84()
+
+	// If I start in the middle of Times Square in New York City, and head due West for
+	// 1000km, where will I end up?
+	NY_lat := 40.757954
+	NY_lon := -73.985548
+	ended_up_at := earth.DirectCalcLatLon(NY_lat, NY_lon, -90, 1000e3)
+	fmt.Println("Ended up at", ended_up_at)
+
+	// Looking on a map, we have ended up in Lafayette Township, a little ways outside
+	// Indianapolis
+
+	// Now let's do the inverse calculation. What is the distance from New York City to
+	// Chicago?
+	CHI_lat := 41.882609
+	CHI_lon := -87.621978
+	NYC_to_CHI_dist := earth.InverseCalcDistance(NY_lat, NY_lon, CHI_lat, CHI_lon)
+	fmt.Printf("Distance from NYC to CHI is %0.1f m\n", NYC_to_CHI_dist)
+
+	// Wyoming is a fairly rectangular state. Taking its four corners as its boundaries,
+	// what is its area?
+	WY_corners_lat_lon := [][2]float64{
+		{40.997958, -111.046710},
+		{45.001311, -111.055200},
+		{44.997380, -104.057699},
+		{41.001432, -104.053249},
+	}
+	polygon := geodesic.NewPolygonArea(earth, false)
+	for _, corner := range WY_corners_lat_lon {
+		polygon.AddPoint(corner[0], corner[1])
+	}
+	polygon_result := polygon.Compute(true, false)
+	fmt.Printf("Wyoming area is approximatley %0.0f m^2\n", polygon_result.Area)
+
+	// What is the approximate perimeter of Wyoming?
+	fmt.Printf("Wyoming perimeter is approximately %0.0f m\n", polygon_result.Perimeter)
+
+	// But we don't only have to do calculations on Earth. Let's try some on Mars!
+	mars_equatorial_radius_m := 3396.2e3
+	mars_flattening_factor := 5.0304e-3
+	mars := geodesic.NewGeodesic(mars_equatorial_radius_m, mars_flattening_factor)
+
+	// What is the distance from Olympus Mons (18.65, -133.8) to the Curiosity Rover's
+	// landing site (-4.47, 137.42)?
+	mars_distance := mars.InverseCalcDistance(18.65, -133.8, -4.47, 137.42)
+	fmt.Printf("Olympus Mons to Curiosity landing site is %0.0f m", mars_distance)
+
+	// Output:
+	// Ended up at {40.15431701948773 -85.75720579845405}
+	// Distance from NYC to CHI is 1147311.9 m
+	// Wyoming area is approximatley 253282066939 m^2
+	// Wyoming perimeter is approximately 2028472 m
+	// Olympus Mons to Curiosity landing site is 5348380 m
+}