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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2006-2009, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id: Random.scala 14498 2008-04-04 12:12:27Z washburn $
package scala.util
/**
* @author Stephane Micheloud
*/
class Random(self0: System.Random) {
private var rnd = self0 // see setSeed(seed)
def self = rnd
/** Creates a new random number generator using a single long seed. */
def this(seed: Long) = this(new System.Random(seed.toInt))
/** Creates a new random number generator using a single integer seed. */
def this(seed: Int) = this(new System.Random(seed))
/** Creates a new random number generator. */
def this() = this(new System.Random(System.Environment.TickCount))
/** Returns the next pseudorandom, uniformly distributed boolean value
* from this random number generator's sequence.
*/
def nextBoolean(): Boolean = (nextInt() & 0x1) == 1
/** Generates random bytes and places them into a user-supplied byte
* array.
*/
def nextBytes(bytes: Array[Byte]) { rnd.NextBytes(bytes) }
/** Returns the next pseudorandom, uniformly distributed double value
* between 0.0 and 1.0 from this random number generator's sequence.
*/
def nextDouble(): Double = rnd.NextDouble()
/** Returns the next pseudorandom, uniformly distributed float value
* between 0.0 and 1.0 from this random number generator's sequence.
*/
def nextFloat(): Float = nextDouble().toFloat
/** Returns the next pseudorandom, Gaussian ("normally") distributed
* double value with mean 0.0 and standard deviation 1.0 from this
* random number generator's sequence.
* This implements the Box-Muller transformation on the pseudorandom
* `nextDouble` method of this class, and should be equivalent to
* the implementation of `nextGaussian` in the Java API.
*/
def nextGaussian(): Double = synchronized {
if (nextGaussianAvailable) {
nextGaussianAvailable = false
nextGaussianCache
} else {
var u: Double = 0.0
var v: Double = 0.0
var s: Double = 0.0
do {
u = 2 * nextDouble() - 1 // [-1, +1]
v = 2 * nextDouble() - 1 // [-1, +1]
s = Math.pow(u, 2) + Math.pow(v, 2)
} while (s >= 1 || s == 0);
val mul = Math.sqrt((-2 * Math.log(s)) / s)
nextGaussianCache = u * mul
nextGaussianAvailable = true
v * mul
}
}
private var nextGaussianAvailable: Boolean = false
private var nextGaussianCache: Double = _
/** Returns the next pseudorandom, uniformly distributed int value
* from this random number generator's sequence.
*/
def nextInt(): Int = rnd.Next()
/** Returns a pseudorandom, uniformly distributed int value between 0
* (inclusive) and the specified value (exclusive), drawn from this
* random number generator's sequence.
*/
def nextInt(n: Int): Int = rnd.Next(0, n)
/** Returns the next pseudorandom, uniformly distributed long value
* from this random number generator's sequence.
*/
def nextLong(): Long = nextInt().toLong // 2x nextInt() ?!
def setSeed(seed: Long) { rnd = new System.Random(seed.toInt) }
}
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