Add geometric_progression

snippets/geometric_progression.md

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+---
+title: geometric_progression
+tags: math,list,intermediate
+---
+
+Initializes a list containing the numbers in the specified range where `start` and `end` are inclusive and the ratio between two terms is `step`.
+Returns an error if `step` equals `1`.
+
+- 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.
+- 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(0, 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]
+```