Data commit

Task/Angle-difference-between-two-bearings/JavaScript/angle-difference-between-two-bearings-1.js

@@ -0,0 +1,35 @@
+function relativeBearing(b1Rad, b2Rad)
+{
+	b1y = Math.cos(b1Rad);
+	b1x = Math.sin(b1Rad);
+	b2y = Math.cos(b2Rad);
+	b2x = Math.sin(b2Rad);
+	crossp = b1y * b2x - b2y * b1x;
+	dotp = b1x * b2x + b1y * b2y;
+	if(crossp > 0.)
+		return Math.acos(dotp);
+	return -Math.acos(dotp);
+}
+
+function test()
+{
+	var deg2rad = 3.14159265/180.0;
+	var rad2deg = 180.0/3.14159265;
+	return "Input in -180 to +180 range\n"
+		+relativeBearing(20.0*deg2rad, 45.0*deg2rad)*rad2deg+"\n"
+		+relativeBearing(-45.0*deg2rad, 45.0*deg2rad)*rad2deg+"\n"
+		+relativeBearing(-85.0*deg2rad, 90.0*deg2rad)*rad2deg+"\n"
+		+relativeBearing(-95.0*deg2rad, 90.0*deg2rad)*rad2deg+"\n"
+		+relativeBearing(-45.0*deg2rad, 125.0*deg2rad)*rad2deg+"\n"
+		+relativeBearing(-45.0*deg2rad, 145.0*deg2rad)*rad2deg+"\n"
+
+		+relativeBearing(29.4803*deg2rad, -88.6381*deg2rad)*rad2deg+"\n"
+		+relativeBearing(-78.3251*deg2rad, -159.036*deg2rad)*rad2deg+"\n"
+	
+		+ "Input in wider range\n"
+		+relativeBearing(-70099.74233810938*deg2rad, 29840.67437876723*deg2rad)*rad2deg+"\n"
+		+relativeBearing(-165313.6666297357*deg2rad, 33693.9894517456*deg2rad)*rad2deg+"\n"
+		+relativeBearing(1174.8380510598456*deg2rad, -154146.66490124757*deg2rad)*rad2deg+"\n"
+		+relativeBearing(60175.77306795546*deg2rad, 42213.07192354373*deg2rad)*rad2deg+"\n";
+
+}

Task/Angle-difference-between-two-bearings/JavaScript/angle-difference-between-two-bearings-2.js

@@ -0,0 +1,75 @@
+(() => {
+    "use strict";
+
+    // ------ ANGLE DIFFERENCE BETWEEN TWO BEARINGS ------
+
+    // bearingDelta :: Radians -> Radians -> Radians
+    const bearingDelta = a =>
+        // The difference between two bearings: a and b.
+        b => {
+            const [ax, ay] = [sin(a), cos(a)];
+            const [bx, by] = [sin(b), cos(b)];
+
+            // Cross-product above zero ?
+            const sign = ((ay * bx) - (by * ax)) > 0 ? (
+                +1
+            ) : -1;
+
+            // Sign * dot-product.
+            return sign * acos((ax * bx) + (ay * by));
+        };
+
+
+    // ---------------------- TEST -----------------------
+    // main :: IO ()
+    const main = () => [
+            [20, 45],
+            [-45, 45],
+            [-85, 90],
+            [-95, 90],
+            [-45, 125],
+            [-45, 145]
+        ].map(xy => showMap(...xy))
+        .join("\n");
+
+
+    // ------------------- FORMATTING --------------------
+
+    // showMap :: Degrees -> Degrees -> String
+    const showMap = (da, db) => {
+        const
+            delta = degreesFromRadians(
+                bearingDelta(
+                    radiansFromDegrees(da)
+                )(
+                    radiansFromDegrees(db)
+                )
+            )
+            .toPrecision(4),
+            theta = `${da}° +`.padStart(6, " "),
+            theta1 = ` ${db}°  ->  `.padStart(11, " "),
+            diff = `${delta}°`.padStart(7, " ");
+
+        return `${theta}${theta1}${diff}`;
+    };
+
+    // --------------------- GENERIC ---------------------
+
+    // radiansFromDegrees :: Float -> Float
+    const radiansFromDegrees = n =>
+        Pi * n / 180.0;
+
+    // degreesFromRadians :: Float -> Float
+    const degreesFromRadians = x =>
+        180.0 * x / Pi;
+
+    // Abbreviations for trigonometric methods and
+    // properties of the standard Math library.
+    const [
+        Pi, sin, cos, acos
+    ] = ["PI", "sin", "cos", "acos"]
+    .map(k => Math[k]);
+
+    // MAIN ---
+    return main();
+})();