C#自带的Random rnd = new Random() ,以时间作为随机数种子,在计算机高速运作中可能出现相同值
以下方式获取随机数种子
来源：http://archive.msdn.microsoft.com/MersenneTwister/Release/ProjectReleases.aspx?ReleaseId=529
protected void Button2_Click(object sender, EventArgs e)
{
//===1.===
int seed = Math.Abs((int)BitConverter.ToUInt32(Guid.NewGuid().ToByteArray(), 0));
Console.WriteLine("seed=" + seed);
//===2.===
byte[] rng = new byte[32];
System.Security.Cryptography.RandomNumberGenerator RndSeed = System.Security.Cryptography.RandomNumberGenerator.Create();
RndSeed.GetBytes(rng);
int seed1 = Math.Abs(BitConverter.ToInt32(rng, 0));
Console.WriteLine("seed1=" + seed1);
//===================================
Random random=new Random(seed);
NPack.MersenneTwister mt = new NPack.MersenneTwister(seed);
NPack.MersenneTwister mt1 = new NPack.MersenneTwister(seed1);
for (int i = 0; i < 50; i++)
{ Console.WriteLine(random.Next(50)); }
Console.ReadLine();
for (int i = 0; i < 50; i++)
{ Console.WriteLine(mt.Next(50)); }
Console.ReadLine();
for (int i = 0; i < 50; i++)
{ Console.WriteLine(mt1.Next(50)); }
Console.ReadLine();
}
}
namespace NPack
{
/// <summary>
/// Generates pseudo-random numbers using the Mersenne Twister algorithm.
/// </summary>
/// <remarks>
/// See <a href="http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html">
/// http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html%3C/a> for details
/// on the algorithm.
/// </remarks>
public class MersenneTwister : Random
{
/// <summary>
/// Creates a new pseudo-random number generator with a given seed.
/// </summary>
/// <param name="seed">A value to use as a seed.</param>
public MersenneTwister(Int32 seed)
{
init((UInt32)seed);
}
/// <summary>
/// Creates a new pseudo-random number generator with a default seed.
/// </summary>
/// <remarks>
/// <c>new <see cref="System.Random"/>().<see cref="Random.Next()"/></c>
/// is used for the seed.
/// </remarks>
public MersenneTwister()
: this(new Random().Next()) /* a default initial seed is used */
{ }
/// <summary>
/// Creates a pseudo-random number generator initialized with the given array.
/// </summary>
/// <param name="initKey">The array for initializing keys.</param>
public MersenneTwister(Int32[] initKey)
{
if (initKey == null)
{
throw new ArgumentNullException("initKey");
}
UInt32[] initArray = new UInt32[initKey.Length];
for (int i = 0; i < initKey.Length; ++i)
{
initArray[i] = (UInt32)initKey[i];
}
init(initArray);
}
public MersenneTwister(Random rnd)
{
// TODO: Complete member initialization
this.rnd = rnd;
}
/// <summary>
/// Returns the next pseudo-random <see cref="UInt32"/>.
/// </summary>
/// <returns>A pseudo-random <see cref="UInt32"/> value.</returns>
//[CLSCompliant(false)]
public virtual UInt32 NextUInt32()
{
return GenerateUInt32();
}
/// <summary>
/// Returns the next pseudo-random <see cref="UInt32"/>
/// up to <paramref name="maxValue"/>.
/// </summary>
/// <param name="maxValue">
/// The maximum value of the pseudo-random number to create.
/// </param>
/// <returns>
/// A pseudo-random <see cref="UInt32"/> value which is at most <paramref name="maxValue"/>.
/// </returns>
//[CLSCompliant(false)]
public virtual UInt32 NextUInt32(UInt32 maxValue)
{
return (UInt32)(GenerateUInt32() / ((Double)UInt32.MaxValue / maxValue));
}
/// <summary>
/// Returns the next pseudo-random <see cref="UInt32"/> at least
/// <paramref name="minValue"/> and up to <paramref name="maxValue"/>.
/// </summary>
/// <param name="minValue">The minimum value of the pseudo-random number to create.</param>
/// <param name="maxValue">The maximum value of the pseudo-random number to create.</param>
/// <returns>
/// A pseudo-random <see cref="UInt32"/> value which is at least
/// <paramref name="minValue"/> and at most <paramref name="maxValue"/>.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">
/// If <c><paramref name="minValue"/> >= <paramref name="maxValue"/></c>.
/// </exception>
//[CLSCompliant(false)]
public virtual UInt32 NextUInt32(UInt32 minValue, UInt32 maxValue) /* throws ArgumentOutOfRangeException */
{
if (minValue >= maxValue)
{
throw new ArgumentOutOfRangeException();
}
return (UInt32)(GenerateUInt32() / ((Double)UInt32.MaxValue / (maxValue - minValue)) + minValue);
}
/// <summary>
/// Returns the next pseudo-random <see cref="Int32"/>.
/// </summary>
/// <returns>A pseudo-random <see cref="Int32"/> value.</returns>
public override Int32 Next()
{
return Next(Int32.MaxValue);
}
/// <summary>
/// Returns the next pseudo-random <see cref="Int32"/> up to <paramref name="maxValue"/>.
/// </summary>
/// <param name="maxValue">The maximum value of the pseudo-random number to create.</param>
/// <returns>
/// A pseudo-random <see cref="Int32"/> value which is at most <paramref name="maxValue"/>.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">
/// When <paramref name="maxValue"/> < 0.
/// </exception>
public override Int32 Next(Int32 maxValue)
{
if (maxValue <= 1)
{
if (maxValue < 0)
{
throw new ArgumentOutOfRangeException();
}
return 0;
}
return (Int32)(NextDouble() * maxValue);
}
/// <summary>
/// Returns the next pseudo-random <see cref="Int32"/>
/// at least <paramref name="minValue"/>
/// and up to <paramref name="maxValue"/>.
/// </summary>
/// <param name="minValue">The minimum value of the pseudo-random number to create.</param>
/// <param name="maxValue">The maximum value of the pseudo-random number to create.</param>
/// <returns>A pseudo-random Int32 value which is at least <paramref name="minValue"/> and at
/// most <paramref name="maxValue"/>.</returns>
/// <exception cref="ArgumentOutOfRangeException">
/// If <c><paramref name="minValue"/> >= <paramref name="maxValue"/></c>.
/// </exception>
public override Int32 Next(Int32 minValue, Int32 maxValue)
{
if (maxValue <= minValue)
{
throw new ArgumentOutOfRangeException();
}
if (maxValue == minValue)
{
return minValue;
}
return Next(maxValue - minValue) + minValue;
}
/// <summary>
/// Fills a buffer with pseudo-random bytes.
/// </summary>
/// <param name="buffer">The buffer to fill.</param>
/// <exception cref="ArgumentNullException">
/// If <c><paramref name="buffer"/> == <see langword="null"/></c>.
/// </exception>
public override void NextBytes(Byte[] buffer)
{
// [codekaizen: corrected this to check null before checking length.]
if (buffer == null)
{
throw new ArgumentNullException();
}
Int32 bufLen = buffer.Length;
for (Int32 idx = 0; idx < bufLen; ++idx)
{
buffer[idx] = (Byte)Next(256);
}
}
/// <summary>
/// Returns the next pseudo-random <see cref="Double"/> value.
/// </summary>
/// <returns>A pseudo-random double floating point value.</returns>
/// <remarks>
/// <para>
/// There are two common ways to create a double floating point using MT19937:
/// using <see cref="GenerateUInt32"/> and dividing by 0xFFFFFFFF + 1,
/// or else generating two double words and shifting the first by 26 bits and
/// adding the second.
/// </para>
/// <para>
/// In a newer measurement of the randomness of MT19937 published in the
/// journal "Monte Carlo Methods and Applications, Vol. 12, No. 5-6, pp. 385 –§C 393 (2006)"
/// entitled "A Repetition Test for Pseudo-Random Number Generators",
/// it was found that the 32-bit version of generating a double fails at the 95%
/// confidence level when measuring for expected repetitions of a particular
/// number in a sequence of numbers generated by the algorithm.
/// </para>
/// <para>
/// Due to this, the 53-bit method is implemented here and the 32-bit method
/// of generating a double is not. If, for some reason,
/// the 32-bit method is needed, it can be generated by the following:
/// <code>
/// (Double)NextUInt32() / ((UInt64)UInt32.MaxValue + 1);
/// </code>
/// </para>
/// </remarks>
public override Double NextDouble()
{
return compute53BitRandom(0, InverseOnePlus53BitsOf1s);
}
/// <summary>
/// Returns a pseudo-random number greater than or equal to zero, and
/// either strictly less than one, or less than or equal to one,
/// depending on the value of the given parameter.
/// </summary>
/// <param name="includeOne">
/// If <see langword="true"/>, the pseudo-random number returned will be
/// less than or equal to one; otherwise, the pseudo-random number returned will
/// be strictly less than one.
/// </param>
/// <returns>
/// If <paramref name="includeOne"/> is <see langword="true"/>,
/// this method returns a double-precision pseudo-random number greater than
/// or equal to zero, and less than or equal to one.
/// If <paramref name="includeOne"/> is <see langword="false"/>, this method
/// returns a double-precision pseudo-random number greater than or equal to zero and
/// strictly less than one.
/// </returns>
public Double NextDouble(Boolean includeOne)
{
return includeOne ? compute53BitRandom(0, Inverse53BitsOf1s) : NextDouble();
}
/// <summary>
/// Returns a pseudo-random number greater than 0.0 and less than 1.0.
/// </summary>
/// <returns>A pseudo-random number greater than 0.0 and less than 1.0.</returns>
public Double NextDoublePositive()
{
return compute53BitRandom(0.5, Inverse53BitsOf1s);
}
/// <summary>
/// Returns a pseudo-random number between 0.0 and 1.0.
/// </summary>
/// <returns>
/// A single-precision floating point number greater than or equal to 0.0,
/// and less than 1.0.
/// </returns>
public Single NextSingle()
{
return (Single)NextDouble();
}
/// <summary>
/// Returns a pseudo-random number greater than or equal to zero, and either strictly
/// less than one, or less than or equal to one, depending on the value of the
/// given boolean parameter.
/// </summary>
/// <param name="includeOne">
/// If <see langword="true"/>, the pseudo-random number returned will be
/// less than or equal to one; otherwise, the pseudo-random number returned will
/// be strictly less than one.
/// </param>
/// <returns>
/// If <paramref name="includeOne"/> is <see langword="true"/>, this method returns a
/// single-precision pseudo-random number greater than or equal to zero, and less
/// than or equal to one. If <paramref name="includeOne"/> is <see langword="false"/>,
/// this method returns a single-precision pseudo-random number greater than or equal to zero and
/// strictly less than one.
/// </returns>
public Single NextSingle(Boolean includeOne)
{
return (Single)NextDouble(includeOne);
}
/// <summary>
/// Returns a pseudo-random number greater than 0.0 and less than 1.0.
/// </summary>
/// <returns>A pseudo-random number greater than 0.0 and less than 1.0.</returns>
public Single NextSinglePositive()
{
return (Single)NextDoublePositive();
}
/// <summary>
/// Generates a new pseudo-random <see cref="UInt32"/>.
/// </summary>
/// <returns>A pseudo-random <see cref="UInt32"/>.</returns>
//[CLSCompliant(false)]
protected UInt32 GenerateUInt32()
{
UInt32 y;
/* _mag01[x] = x * MatrixA for x=0,1 */
if (_mti >= N) /* generate N words at one time */
{
Int16 kk = 0;
for (; kk < N - M; ++kk)
{
y = (_mt[kk] & UpperMask) | (_mt[kk + 1] & LowerMask);
_mt[kk] = _mt[kk + M] ^ (y >> 1) ^ _mag01[y & 0x1];
}
for (; kk < N - 1; ++kk)
{
y = (_mt[kk] & UpperMask) | (_mt[kk + 1] & LowerMask);
_mt[kk] = _mt[kk + (M - N)] ^ (y >> 1) ^ _mag01[y & 0x1];
}
y = (_mt[N - 1] & UpperMask) | (_mt[0] & LowerMask);
_mt[N - 1] = _mt[M - 1] ^ (y >> 1) ^ _mag01[y & 0x1];
_mti = 0;
}
y = _mt[_mti++];
y ^= temperingShiftU(y);
y ^= temperingShiftS(y) & TemperingMaskB;
y ^= temperingShiftT(y) & TemperingMaskC;
y ^= temperingShiftL(y);
return y;
}
/* Period parameters */
private const Int32 N = 624;
private const Int32 M = 397;
private const UInt32 MatrixA = 0x9908b0df; /* constant vector a */
private const UInt32 UpperMask = 0x80000000; /* most significant w-r bits */
private const UInt32 LowerMask = 0x7fffffff; /* least significant r bits */
/* Tempering parameters */
private const UInt32 TemperingMaskB = 0x9d2c5680;
private const UInt32 TemperingMaskC = 0xefc60000;
private static UInt32 temperingShiftU(UInt32 y)
{
return (y >> 11);
}
private static UInt32 temperingShiftS(UInt32 y)
{
return (y << 7);
}
private static UInt32 temperingShiftT(UInt32 y)
{
return (y << 15);
}
private static UInt32 temperingShiftL(UInt32 y)
{
return (y >> 18);
}
private readonly UInt32[] _mt = new UInt32[N]; /* the array for the state vector */
private Int16 _mti;
private static readonly UInt32[] _mag01 = { 0x0, MatrixA };
private void init(UInt32 seed)
{
_mt[0] = seed & 0xffffffffU;
for (_mti = 1; _mti < N; _mti++)
{
_mt[_mti] = (uint)(1812433253U * (_mt[_mti - 1] ^ (_mt[_mti - 1] >> 30)) + _mti);
// See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier.
// In the previous versions, MSBs of the seed affect
// only MSBs of the array _mt[].
// 2002/01/09 modified by Makoto Matsumoto
_mt[_mti] &= 0xffffffffU;
// for >32 bit machines
}
}
private void init(UInt32[] key)
{
Int32 i, j, k;
init(19650218U);
Int32 keyLength = key.Length;
i = 1; j = 0;
k = (N > keyLength ? N : keyLength);
for (; k > 0; k--)
{
_mt[i] = (uint)((_mt[i] ^ ((_mt[i - 1] ^ (_mt[i - 1] >> 30)) * 1664525U)) + key[j] + j); /* non linear */
_mt[i] &= 0xffffffffU; // for WORDSIZE > 32 machines
i++; j++;
if (i >= N) { _mt[0] = _mt[N - 1]; i = 1; }
if (j >= keyLength) j = 0;
}
for (k = N - 1; k > 0; k--)
{
_mt[i] = (uint)((_mt[i] ^ ((_mt[i - 1] ^ (_mt[i - 1] >> 30)) * 1566083941U)) - i); /* non linear */
_mt[i] &= 0xffffffffU; // for WORDSIZE > 32 machines
i++;
if (i < N)
{
continue;
}
_mt[0] = _mt[N - 1]; i = 1;
}
_mt[0] = 0x80000000U; // MSB is 1; assuring non-zero initial array
}
// 9007199254740991.0 is the maximum double value which the 53 significand
// can hold when the exponent is 0.
private const Double FiftyThreeBitsOf1s = 9007199254740991.0;
// Multiply by inverse to (vainly?) try to avoid a division.
private const Double Inverse53BitsOf1s = 1.0 / FiftyThreeBitsOf1s;
private const Double OnePlus53BitsOf1s = FiftyThreeBitsOf1s + 1;
private const Double InverseOnePlus53BitsOf1s = 1.0 / OnePlus53BitsOf1s;
private Random rnd;
private Double compute53BitRandom(Double translate, Double scale)
{
// get 27 pseudo-random bits
UInt64 a = (UInt64)GenerateUInt32() >> 5;
// get 26 pseudo-random bits
UInt64 b = (UInt64)GenerateUInt32() >> 6;
// shift the 27 pseudo-random bits (a) over by 26 bits (* 67108864.0) and
// add another pseudo-random 26 bits (+ b).
return ((a * 67108864.0 + b) + translate) * scale;
// What about the following instead of the above? Is the multiply better?
// Why? (Is it the FMUL instruction? Does this count in .Net? Will the JITter notice?)
//return BitConverter.Int64BitsToDouble((a << 26) + b));
}
}
}