[Tutor] clearing a text document

Kent Johnson kent37 at tds.net
Thu Aug 30 12:53:59 CEST 2007


max baseman wrote:
> right it's for a quick math "game" the rules are simple you start  
> with any number to get the next number you, a. if it's odd multiply  
> by 3 than add 1 or b. if it's even divide by two,  the point of this  
> is to see how long it takes to get to one are it starts to repeat  
> 4,2,1,4,2,1...
> now im looking for a a number with  a very high amount of numbers  
> till you get to 1 so every time it's finds a new one i would like it  
> to write that to a file and clear the last entry,

If your goal is to find long sequences why not write your program to try 
every number up to some limit and find the longest?

It's a nice use of generators, for those who know what they are...

These sequences are known as hailstone numbers. The (unproven) 
conjecture that the sequence will always terminate is called Collatz' 
Conjecture. Some interesting info and pictures here:
http://sprott.physics.wisc.edu/pickover/hailstone.html
http://mathworld.wolfram.com/CollatzProblem.html

Kent


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