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| author | Dmitry Vyukov <dvyukov@google.com> | 2017-12-13 16:34:10 +0100 |
|---|---|---|
| committer | Dmitry Vyukov <dvyukov@google.com> | 2017-12-17 11:39:14 +0100 |
| commit | e3b5ea9797c9efc179d48eadf866561eb9cdebd8 (patch) | |
| tree | 76d83aa5bcd06debc16017976b7605e73e713a09 | |
| parent | b5b6142df447bafa795931b4e068085a92ca2f89 (diff) | |
prog: fix an unfortunate case of non-determinism
We used the math/rand global prng in biasedRand historically.
Fix that.
| -rw-r--r-- | prog/rand.go | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/prog/rand.go b/prog/rand.go index 839c6d1c3..b99399c9d 100644 --- a/prog/rand.go +++ b/prog/rand.go @@ -103,7 +103,7 @@ func (r *randGen) randRangeInt(begin uint64, end uint64) uint64 { // probability of n-1 is k times higher than probability of 0. func (r *randGen) biasedRand(n, k int) int { nf, kf := float64(n), float64(k) - rf := nf * (kf/2 + 1) * rand.Float64() + rf := nf * (kf/2 + 1) * r.Float64() bf := (-1 + math.Sqrt(1+2*kf*rf/nf)) * nf / kf return int(bf) } |