feat(random): add IRandom.probability()

- add impl for ARandom base class
thi-ng · Aug 12, 2023 · efdd49c · efdd49c
1 parent 58fc51c
commit efdd49c
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Showing 3 changed files with 13 additions and 2 deletions.
diff --git a/packages/random/src/api.ts b/packages/random/src/api.ts
@@ -15,7 +15,7 @@ export interface INorm {
 	norm(scale?: number): number;
 	/**
 	 * Similar to {@link INorm.norm}, but returns values in either the
-	 * `[min..max)` or in the `(-max...min]` interval (i.e. excluding values in
+	 * `[min..max)` or in the `(-max...-min]` interval (i.e. excluding values in
 	 * the `(-min..min)` range). Both `min` and `max` MUST be >= 0.
 	 *
 	 * @remarks
@@ -44,6 +44,13 @@ export interface IRandom extends INorm {
 	 * @param max - default 1
 	 */
 	float(max?: number): number;
+	/**
+	 *  Calls {@link IRandom.float} and returns true iff result is < `p`
+	 *  (assumed to be in [0..1] interval).
+	 *
+	 * @param p
+	 */
+	probability(p: number): boolean;
 	/**
 	 * Returns float in [min..max) interval.
 	 *

diff --git a/packages/random/src/arandom.ts b/packages/random/src/arandom.ts
@@ -9,6 +9,10 @@ export abstract class ARandom implements IRandom {
 		return this.int() * INV_MAX * norm;
 	}
 
+	probability(p: number) {
+		return this.float() < p;
+	}
+
 	norm(norm = 1) {
 		return (this.int() * INV_MAX - 0.5) * 2 * norm;
 	}

diff --git a/packages/random/src/coin.ts b/packages/random/src/coin.ts
@@ -6,7 +6,7 @@ import { SYSTEM } from "./system.js";
  * quality of given {@link IRandom}) PRNG.
  *
  * @remarks
- * Also see {@link fairCoin}.
+ * Also see {@link fairCoin} and {@link IRandom.probability}.
  *
  * @param rnd -
  */