On May 1, 2009, at 6:06 AM, Craig Ringer wrote:
<snip>
What I'm looking for is a function that, given an input within a
constrained range (say, a 32 bit integer) produces a different output
within the same range. For any given input, the output should be the
same each time, and for any given output there should only be one
input
that results in that output.
I think you drop the idea of a repeatable mapping you may have some
success with the Knuth (aka Fisher-Yates) shuffle algorithm: http://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle
Why does anything need to be repeatable when you only need to make
sure that each number is only generated once?
Erik Jones, Database Administrator
Engine Yard
Support, Scalability, Reliability
866.518.9273 x 260
Location: US/Pacific
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