Here is the fix for bug 1047, consisting of a new signature and new structure. Emden =============== rand-sig.sml ========================= (* rand-sig.sml * * COPYRIGHT (c) 1993 by AT&T Bell Laboratories. See COPYRIGHT file for details. * COPYRIGHT (c) 1998 by AT&T Laboratories. * * Signature for a simple random number generator. * *) signature RAND = sig type rand = Word31.word val randMin : rand val randMax : rand val random : rand -> rand (* Given seed, return value randMin <= v <= randMax * Iteratively using the value returned by random as the * next seed to random will produce a sequence of pseudo-random * numbers. *) val mkRandom : rand -> unit -> rand (* Given seed, return function generating a sequence of * random numbers randMin <= v <= randMax *) val norm : rand -> real (* Map values in the range [randMin,randMax] to (0.0,1.0) *) val range : (int * int) -> rand -> int (* Map v, randMin <= v <= randMax, to integer range [i,j] * Exception - * Fail if j < i *) end (* RAND *) ============== rand.sml ===================== (* rand.sml * * COPYRIGHT (c) 1991 by AT&T Bell Laboratories. See COPYRIGHT file for details * COPYRIGHT (c) 1998 by AT&T Laboratories. See COPYRIGHT file for details * * Random number generator taken from Paulson, pp. 170-171. * Recommended by Stephen K. Park and Keith W. Miller, * Random number generators: good ones are hard to find, * CACM 31 (1988), 1192-1201 * Updated to include the new preferred multiplier of 48271 * CACM 36 (1993), 105-110 * Updated to use on Word31. * * Note: The Random structure provides a better generator. *) structure Rand : RAND = struct type rand = Word31.word type rand' = Int32.int (* internal representation *) val a : rand' = 48271 val m : rand' = 2147483647 (* 2^31 - 1 *) val m_1 = m - 1 val q = m div a val r = m mod a val extToInt = Int32.fromLarge o Word31.toLargeInt val intToExt = Word31.fromLargeInt o Int32.toLarge val randMin : rand = 0w1 val randMax : rand = intToExt m_1 fun chk 0w0 = 1 | chk 0wx7fffffff = m_1 | chk seed = extToInt seed fun random' seed = let val hi = seed div q val lo = seed mod q val test = a * lo - r * hi in if test > 0 then test else test + m end val random = intToExt o random' o chk fun mkRandom seed = let val seed = ref (chk seed) in fn () => (seed := random' (!seed); intToExt (!seed)) end val real_m = Real.fromLargeInt (Int32.toLarge m) fun norm s = (Real.fromLargeInt (Word31.toLargeInt s)) / real_m fun range (i,j) = if j < i then LibBase.failure{module="Random",func="range",msg="hi < lo"} else if j = i then fn _ => i else let val R = Int32.fromInt j - Int32.fromInt i val cvt = Word31.toIntX o Word31.fromLargeInt o Int32.toLarge in if R = m then Word31.toIntX else fn s => i + cvt ((extToInt s) mod (R+1)) end end (* Rand *)
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The output has ended thus: toIntX else fn s => i + cvt ((extToInt s) mod (R+1)) end end (* Rand *)