Consolidate arithmetic and geometric progression

content/redirects.yaml

@@ -2638,3 +2638,9 @@
 - from: /js/s/pad-number
   to: /js/s/number-formatting
   status: 301!
+- from: /js/s/arithmetic-progression
+  to: /js/s/arithmetic-and-geometric-progression
+  status: 301!
+- from: /js/s/geometric-progression
+  to: /js/s/arithmetic-and-geometric-progression
+  status: 301!

content/snippets/js/s/arithmetic-and-geometric-progression.md

@@ -0,0 +1,42 @@
+---
+title: Arithmetic and geometric progression in JavaScript
+shortTitle: Arithmetic and geometric progression
+type: story
+language: javascript
+tags: [math,algorithm]
+cover: half-trees
+excerpt: Create arrays of numbers in arithmetic and geometric progression.
+dateModified: 2024-02-16
+---
+
+Arithmetic progression refers to a sequence of numbers in which the **difference** between any two successive members is a constant. Geometric progression refers to a sequence of numbers in which the **ratio** between any two successive members is a constant. Both can be easily implemented in JavaScript.
+
+## Arithmetic progression
+
+Given a positive integer `n` and a positive limit `lim`, the task is to create an array of numbers in the arithmetic progression, starting with the given positive integer and up to the specified limit.
+
+In order to do so, you can use `Array.from()` to create an array of the desired length, `lim / n`. Then, use a map function as the second argument to fill it with the desired values in the given range.
+
+```js
+const arithmeticProgression  = (n, lim) =>
+  Array.from({ length: Math.ceil(lim / n) }, (_, i) => (i + 1) * n );
+
+arithmeticProgression(5, 25); // [5, 10, 15, 20, 25]
+```
+
+## Geometric progression
+
+Given a positive integer `end`, and optional positive integers `start` and `step`, the task is to create an array of numbers in the geometric progression, starting with the given positive integer and up to the specified limit.
+
+In order to do so, you can use `Array.from()`, `Math.log()` and `Math.floor()` to create an array of the desired length. Then, use `Array.prototype.map()` to fill it with the desired values in the given range. Omit the second argument, `start`, to use a default value of `1`. Omit the third argument, `step`, to use a default value of `2`.
+
+```js
+const geometricProgression = (end, start = 1, step = 2) =>
+  Array.from({
+    length: Math.floor(Math.log(end / start) / Math.log(step)) + 1,
+  }).map((_, i) => start * step ** i);
+
+geometricProgression(256); // [1, 2, 4, 8, 16, 32, 64, 128, 256]
+geometricProgression(256, 3); // [3, 6, 12, 24, 48, 96, 192]
+geometricProgression(256, 1, 4); // [1, 4, 16, 64, 256]
+```