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Re: custom random number generator

by toro (Beadle)
on Nov 30, 2011 at 07:24 UTC ( #940787=note: print w/replies, xml ) Need Help??

in reply to custom random number generator

Anonymous Monk, you could

  1. do your bell curve trick to produce a standard normal ∈ (−∞, +∞) centred on 0
  2. map the negative half (−∞, 0] thru exp onto 0,1 and thence thru ƒ($num) = x over {1 + y • (1 − $num)} onto [x/y, x].
  3. map the positive half (0, +∞) thru g($rand) = 1−exp(−$rand) onto (0,1) and thence thru h($num) = x • (1 + $num • y) onto (x, xy).
. That will be centred on x, mound-shaped, and put half the probability mass on either side of x — stretched according to your whims.

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