Random Class Reference

#include <Random.h>

List of all members.

Public Member Functions
	Random (void)
	Random (unsigned long seed)
void	init (unsigned long seed)
void	skip (void)
void	split (int iStream, int numStreams)
BigReal	uniform (void)
BigReal	gaussian (void)
Vector	gaussian_vector (void)
long	integer (void)
template<class Elem>
void	reorder (Elem *a, int n)

---

Constructor & Destructor Documentation

Random::Random (  void   )  [inline]

Definition at line 50 of file Random.h. { init(0); rand48_seed = RAND48_SEED; }

Random::Random (  unsigned long  seed  )  [inline]

Definition at line 56 of file Random.h. { init(seed); }

---

Member Function Documentation

BigReal Random::gaussian (  void   )  [inline]

Definition at line 116 of file Random.h. References BigReal. Referenced by Controller::langevinPiston1(), and Controller::langevinPiston2(). { BigReal fac, r, v1, v2; if (second_gaussian_waiting) { second_gaussian_waiting = 0; return second_gaussian; } else { r = 2.; // r >= 1.523e-8 ensures abs result < 6 while (r >=1. || r < 1.523e-8) { // make sure we are within unit circle v1 = 2.0 * uniform() - 1.0; v2 = 2.0 * uniform() - 1.0; r = v1*v1 + v2*v2; } fac = sqrt(-2.0 * log(r)/r); // now make the Box-Muller transformation to get two normally // distributed random numbers. Save one and return the other. second_gaussian_waiting = 1; second_gaussian = v1 * fac; return v2 * fac; } }

Vector Random::gaussian_vector (  void   )  [inline]

Definition at line 139 of file Random.h. Referenced by Controller::langevinPiston1(), Controller::langevinPiston2(), Sequencer::langevinVelocities(), Sequencer::langevinVelocitiesBBK2(), Sequencer::reassignVelocities(), and Sequencer::reinitVelocities(). { return Vector( gaussian(), gaussian(), gaussian() ); }

void Random::init (  unsigned long  seed  )  [inline]

Definition at line 61 of file Random.h. References INT64_LITERAL, and RAND48_SEED. { second_gaussian = 0; second_gaussian_waiting = 0; rand48_seed = seed & INT64_LITERAL(0x00000000ffffffff); rand48_seed = rand48_seed << 16; rand48_seed |= RAND48_SEED & INT64_LITERAL(0x0000ffff); rand48_mult = RAND48_MULT; rand48_add = RAND48_ADD; }

long Random::integer (  void   )  [inline]

Definition at line 144 of file Random.h. References INT64_LITERAL. { skip(); return ( ( rand48_seed >> 17 ) & INT64_LITERAL(0x000000007fffffff) ); }

template<class Elem> void Random::reorder (  Elem *  a, int  n )  [inline]

Definition at line 150 of file Random.h. Referenced by ComputePmeMgr::initialize(), and PmePencil< CBase_PmeZPencil >::order_init(). { for ( int i = 0; i < (n-1); ++i ) { int ie = i + ( integer() % (n-i) ); if ( ie == i ) continue; const Elem e = a[ie]; a[ie] = a[i]; a[i] = e; } }

void Random::skip (  void   )  [inline]

Definition at line 72 of file Random.h. { rand48_seed = ( rand48_seed * rand48_mult + rand48_add ) & RAND48_MASK; }

void Random::split (  int  iStream, int  numStreams )  [inline]

Definition at line 77 of file Random.h. References int64. Referenced by Controller::Controller(), and Sequencer::Sequencer(). { int i; // make sure that numStreams is odd to ensure maximum period numStreams |= 1; // iterate to get to the correct stream for ( i = 0; i < iStream; ++i ) skip(); // save seed and add so we can use skip() for our calculations int64 save_seed = rand48_seed; // calculate c *= ( 1 + a + ... + a^(numStreams-1) ) rand48_seed = rand48_add; for ( i = 1; i < numStreams; ++i ) skip(); int64 new_add = rand48_seed; // calculate a = a^numStreams rand48_seed = rand48_mult; rand48_add = 0; for ( i = 1; i < numStreams; ++i ) skip(); rand48_mult = rand48_seed; rand48_add = new_add; rand48_seed = save_seed; second_gaussian = 0; second_gaussian_waiting = 0; }

BigReal Random::uniform (  void   )  [inline]

Definition at line 109 of file Random.h. References BigReal, and INT64_LITERAL. { skip(); const double exp48 = ( 1.0 / (double)(INT64_LITERAL(1) << 48) ); return ( (double) rand48_seed * exp48 ); }

---

The documentation for this class was generated from the following file:

• Random.h

---