PHP Code:
#ifndef RNGSTREAM_H
#define RNGSTREAM_H
#include <string>
class RngStream
{
public:
RngStream (const char *name = "");
static void SetPackageSeed (const unsigned long seed[6]);
void ResetStartStream ();
void ResetStartSubstream ();
void ResetNextSubstream ();
void SetAntithetic (bool a);
void IncreasedPrecis (bool incp);
/*After calling this method with incp = true, each call to the generator (direct or indirect)
for this stream will return a uniform random number with more bits of resolution (53 bits if
machine follows IEEE 754 standard) instead of 32 bits, and will advance the state of the stream
by 2 steps instead of 1. More precisely, if s is a stream of the class RngStream, in the non-antithetic
case, the instruction “u = s.RandU01()” will be equivalent to “u = (s.RandU01()
+ s.RandU01() * fact) % 1.0” where the constant fact is equal to 2Š 24 . This also applies
when calling RandU01 indirectly (e.g., via RandInt, etc.). By default, or if this method is called
again with incp = false, each call to RandU01 for this stream advances the state by 1 step
and returns a number with 32 bits of resolution.*/
void SetSeed (const unsigned long seed[6]);
/*Sets the initial seed Ig of the stream to the vector seed. The vector seed should contain valid
seed values as described in SetPackageSeed. The state of the stream is then reset to this initial
seed. The states and seeds of the other streams are not modified. As a result, after calling this
method, the initial seeds of the streams are no longer spaced Z values apart. We discourage
the use of this method; proper use of the Reset* methods is preferable.*/
void AdvanceState (long e, long c);
/*Advances the state by n steps (see below for the meaning of n), without modifying the states
of other streams or the values of Bg and Ig in the current object. If e > 0, then n =2 e + c;if
e < 0, then n = Š 2Š e +c;and if e = 0, then n = c.Note: c is allowed to take negative values.
We discourage the use of this method.*/
void GetState (unsigned long seed[6]) const;
//Returns in seed[0..5] the current state Cg of this stream. This is convenient if we want to
//save the state for subsequent use.
void WriteState () const;
//Writes (to standard output) the current state Cg of this stream.
void WriteStateFull () const;
//Writes (to standard output) the value of all the internal variables of this stream: name, anti,
//incPrec, Ig, Bg, Cg.
double RandU01 ();
/*Normally, returns a (pseudo)random number from the uniform distribution over the interval
(0, 1), after advancing the state by one step. The returned number has 32 bits of precision in
the sense that it is always a multiple of 1/(2 32
Š 208). However, if IncreasedPrecis(true) has
been called for this stream, the state is advanced by two steps and the returned number has 53
bits of precision.*/
long RandInt (long i, long j);
//Returns a (pseudo)random number from the discrete uniform distribution over the integers
//{ i, i +1,...,j } . Makes one call to RandU01.
private:
double Cg[6], Bg[6], Ig[6];
//Vectors to store the current seed, the beginning of the current block (substream) and the
//beginning of the current stream.
bool anti, incPrec;
//Variables to indicate whether to generate antithetic or increased precision random numbers.
std::string name;
//String to store the optional name of the current RngStream object.
static double nextSeed[6];
//Static vector to store the beginning state of the next RngStream to be created (instantiated).
double U01 ();
//The backbone uniform random number generator.
double U01d ();
//The backbone uniform random number generator with increased precision.
};
#endif