Angle difference between two bearings: Difference between revisions

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@@ Line 1,640: / Line 1,640: @@
 <lang JavaScript>(() => {
+    "use strict";
+    // ------ ANGLE DIFFERENCE BETWEEN TWO BEARINGS ------
     // bearingDelta :: Radians -> Radians -> Radians
-    const bearingDelta = (ar, br) => {
+    const bearingDelta = a =>
+        // The difference between two bearings: a and b.
-        const [ax, ay] = [sin(ar), cos(ar)], [bx, by] = [sin(br), cos(br)],
+        b => {
+            const [ax, ay] = [sin(a), cos(a)];
+            const [bx, by] = [sin(b), cos(b)];
-        // Cross-product > 0 ?
+            // Cross-product above zero ?
-        sign = ((ay * bx) - (by * ax)) > 0 ? +1 : -1;
+            const sign = ((ay * bx) - (by * ax)) > 0 ? (
+                +1
+            ) : -1;
-        // Sign * dot-product
+            // Sign * dot-product.
-        return sign * acos((ax * bx) + (ay * by));
+            return sign * acos((ax * bx) + (ay * by));
-    };
+        };
-    // Pi, sin, cos, acos :: Function
-    const [Pi, sin, cos, acos] = ['PI', 'sin', 'cos', 'acos']
-    .map(k => Math[k]),
-        degRad = x => Pi * x / 180.0,
-        radDeg = x => 180.0 * x / Pi;
+    // ---------------------- TEST -----------------------
+    // main :: IO ()
-    // TEST ------------------------------------------------------------------
+    const main = () => [
-    // justifyRight :: Int -> Char -> Text -> Text
-    const justifyRight = (n, cFiller, strText) =>
-        n > strText.length ? (
-            (cFiller.repeat(n) + strText)
-            .slice(-n)
-        ) : strText;
-    // showMap :: Degrees -> Degrees -> String
-    const showMap = (da, db) =>
-        justifyRight(6, ' ', `${da}° +`) +
-        justifyRight(11, ' ', ` ${db}°  ->  `) +
-        justifyRight(7, ' ', `${(radDeg(bearingDelta(degRad(da), degRad(db))))
-            .toPrecision(4)}°`);
-    return [
             [20, 45],
             [-45, 45],
@@ Line 1,683: / Line 1,671: @@
             [-45, 145]
         ].map(xy => showMap(...xy))
-        .join('\n');
+        .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 =>
+.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();
 })();</lang>
 {{Out}}