1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Rainbow table reduction function

  1. May 23, 2008 #1
    I recently did some personal research into the aforementioned functions.

    I created a few simple functions based in part on sine (and cosine).
    Anyway, the basic idea was to get a seed from the sine of some number, since -1 =< sin N =< 1.

    However, I think that sine is not an ideal function to get a pseudo-random seed (assuming a pseudo-random input). If f(x) = sin x, then f'(x) = cos x.

    Since the derivative is non-linear, and sine is a smooth function (and also non-linear), then there is a greater chance of picking picking some numbers relative to others.

    EX: for some interval of the function, a small change in x will result in a disproportionate change in f(x) relative to a different interval.
    I would be overjoyed if someone could debunk or backup my assumptions.
  2. jcsd
  3. May 23, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    Since cos(x) is smooth, a small change in x may result in only a small change in sin(x), yes.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook