XP and Math

[Primitive Screwhead]

Hello again!

I have been prepping for a hex-crawl exploration using random generation for content for the OLD system. I cheated and grabbed an online database of 3x monsters and ran a simple conversion process (OLD attributes = 1/2 of DnD attributes). I still need to scrub and clean up the list to add damage and special attacks.. but that is a story for another thread.

What I am working on right now is the XP values.. which is pretty straight forward, and the companion 'level' calculation.. which is not.
I am a fan of algebra/math expressions instead of charts, mainly because I program computers for a living. So looking at the XP chart started giving me a headache.

The current chart gets its values with a stepped increase, stepped on every odd level. From 1 to 2 and 2 to 3 is an increase of 50; 3-4 and 4-5 is 100, 5-6 and 6-7 is 200, etc..
That is impossible to reverse engineer an equation that calculates the level based on the XP.

I would prefer a linear progression based on 1.5 times the previous levels minimum XP value, starting at 67 XP for zero level. This closely matches the current table

0	67
1	101
2	150
3	225
4	300
5	450
6	600
7	900
8	1,200
9	1,800
10	2,400
11	3,600
12	4,800
13	7,200
14	9,600
15	14,400
16	19,200

WIth this table, all I need is someone better at math than I am to reverse the equation

 

[hirou]

I'm not sure I understood you right, are you looking for the equation of geometric progression?
a_n=a₀*rⁿ, in your case a₀=67, r=1.5
If you want to determine the level from the current exp, naturally, it would be n=log_r(current_exp/a₀)

 

[Morrus]

I can't think why somebody would prefer to use something like n=log_r(current_exp/a₀) rather than just look at a table. Computers can look up tables, can't they? But the XP chart isn't intended to provide any kind of artificial aesthetic symmetry. It's very unplaytested, and XP will almost certainly change, mainly based on playtesting.

 

[Primitive Screwhead]

Well, people will generally just look at the table.. which is all fine and well.

Programmers like me that are working on converting the entire 3x SRD monster list to usable creatures tend to like math as it is 'cleaner' code.

As to the 'artificial aesthetic symmetry', your current chart has this one odd levels. To me this clashes with the artificial asymmetry of the even levels and prompts the question of 'why does advancing to an odd level cost 35% {ish} while it costs 56% {ish} to advance to even levels?'

Hence my search for a fully symmetrical answer.