Darwinbots Forum

Bots and Simulations => Bot Tavern => Topic started by: Tilthanseco on August 05, 2012, 12:42:09 AM

Title: Random Bot
Post by: Tilthanseco on August 05, 2012, 12:42:09 AM: I took the random bot idea and used an internal random number generator instead of "rnd".

This way mutations can still affect the bot very well. I'm running this bot as a alga with a simple bot.

Regular Random Bot 0 to 1000
Code: [Select]
cond start 1000 rnd 1000 rnd store stop
Very Simple Internal Generator 0 to 999
Code: [Select]
'Environmental Seed cond *.robage 1 = start *.xpos *.ypos add 2 div 51 store stop 'Location Generator cond start *51 125 mult 31991 mod 51 store *51 1000 mod 52 store stop 'Value Generator to keep from Looping cond *52 51 != start *51 125 mult 31991 mod 51 store *51 1000 mod *52 store stopP.S. Making a random number generator is hard... It took me most of the day to make a random enough one that was simple while limited to a state of 32000.
Many tries led to loops of often only 10 numbers.
Title: Re: Random Bot
Post by: Botsareus on August 05, 2012, 10:44:56 AM: Nice concept. How is this better then using rnd?
Title: Re: Random Bot
Post by: Numsgil on August 05, 2012, 04:44:18 PM: Yeah, random number generators are hard. You might want to read chapter 7 of Numerical Recipes in C (http://astronu.jinr.ru/wiki/upload/d/d6/NumericalRecipesinC.pdf) if you're interested in the subject at all. It's a good introductory chapter on generators and why they're tricky.
Title: Re: Random Bot
Post by: Tilthanseco on August 06, 2012, 01:53:11 AM: Thanks Nums, I read 7.1 and it was interesting and useful. The rest was out of my league...

I found out what my big problem was though, the stack only holds 2^21 and I was thinking 2^32. The stack overflows were leading to my looping problems.

The book says I should use a fraction to limit the rand like: state * 143/1125 but this leads to half as many 0's as other numbers. ???
Using a mod like: state mod 1001 gives the right number of 0's, what's up with that?

I settled on this:
Code: [Select]
'Seed cond *.robage 1 = start *.xpos *.ypos add 9 div 51 store stop 'Location Generator cond start *51 211 mult 1663 add 7875 mod 51 store *51 143 mult 1125 div 52 store stop 'Value Generator cond *52 51 != start *51 211 mult 1663 add 7875 mod 143 mult 1125 div *52 store stop
@Botsareus I figured a random number generator that was able to change would be better than a static Random gen. :P
This new one works almost as well as rnd according to my very limited testing, besides the stupid 0's. (Replacing [143 mult 1125 div] with [1001 mod] fixes that)
I thought you would like it because it lets mutations affect more things.

P.S. The stack is so small, I had to reduce my fraction from 1001/7875 to 143/1125 :wacko:
Title: Re: Random Bot
Post by: Botsareus on August 06, 2012, 12:01:48 PM: oh 8)
Title: Re: Random Bot
Post by: Numsgil on August 07, 2012, 02:18:29 AM: Yeah, the stack cap is pretty tough once you start getting in to any sort of numerical algorithms. You have to get really creative.