time for a snapshot

workshop/steps/02-vectors-length/mathv.ts

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+import type { Vec } from "./given.ts";
+
+/** The length (magnitude) of the arrow. */
+export function length(a: Vec): number {
+	return Math.sqrt(a.x * a.x + a.y * a.y);
+}
+
+/**
+ * A unit-length vector pointing the same way as `a`.
+ * MUST return (0, 0) when `a` is the zero vector — do not divide by zero.
+ */
+export function normalize(a: Vec): Vec {
+	const len = length(a);
+	const x = a.x === 0 ? 0 : a.x / len;
+	const y = a.y === 0 ? 0 : a.y / len;
+
+	return { x, y };
+}
+
+/** The dot product a·b. */
+export function dot(a: Vec, b: Vec): number {
+	return a.x * b.x + a.y * b.y;
+}