31 lines
1.1 KiB
Markdown
31 lines
1.1 KiB
Markdown
---
|
|
title: Geometric progression
|
|
type: snippet
|
|
language: python
|
|
tags: [math,list]
|
|
cover: kettle-laptop
|
|
excerpt: Initializes a list containing the numbers in the specified geometric progression range.
|
|
dateModified: 2020-11-02T19:28:05+02:00
|
|
---
|
|
|
|
Initializes a list containing the numbers in the specified range where `start` and `end` are inclusive and the ratio between two terms is `step`.
|
|
|
|
- Use `range()`, `math.log()` and `math.floor()` and a list comprehension to create a list of the appropriate length, applying the step for each element.
|
|
- Returns an error if `step` equals `1`.
|
|
- Omit the second argument, `start`, to use a default value of `1`.
|
|
- Omit the third argument, `step`, to use a default value of `2`.
|
|
|
|
```py
|
|
from math import floor, log
|
|
|
|
def geometric_progression(end, start=1, step=2):
|
|
return [start * step ** i for i in range(floor(log(end / start)
|
|
/ log(step)) + 1)]
|
|
```
|
|
|
|
```py
|
|
geometric_progression(256) # [1, 2, 4, 8, 16, 32, 64, 128, 256]
|
|
geometric_progression(256, 3) # [3, 6, 12, 24, 48, 96, 192]
|
|
geometric_progression(256, 1, 4) # [1, 4, 16, 64, 256]
|
|
```
|