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kdelibs'KRandomSequence (./kdelibs/kdecore/krandomsequence.h:37)

class KRandomSequence
{
public: 
  /**
   * Creates a pseudo-random sequence based on the seed lngSeed.
   * 
   * @param lngSeed Seed to initialize the sequence with.
   *
   * If lngSeed is 0, the sequence is initialized with a value from
   * kapp->random().
   *
   * A Pseudo-random sequence is different for each seed but can be 
   * reproduced by starting the sequence with the same seed.
   *
   * If you need a single value which needs to be unpredictable, 
   * you need to use kapp->random() instead.
   * 
   */
  KRandomSequence( long lngSeed = 0 );

  /**
   * Standard destructor
   */
  virtual ~KRandomSequence();

  /**
   * Restart the sequence based on lngSeed
   */
  void setSeed( long lngSeed = 1 );

  /**
   * Get the next number from the pseudo-random sequence
   *
   * @return a psuedo-random double value between [0,1[
   */
  double getDouble(); 
  
  /**
   * Get the next number from the pseudo-random sequence
   *
   * @return a pseudo-random integer value between [0, max[
   * with 0 < max <= 1.000.000
   */
  unsigned long getLong(unsigned long max); 

	
private:
  void Draw(); // Generate the random number
  long m_lngSeed1;
  long m_lngSeed2;
  long m_lngShufflePos;

  static const int    m_nShuffleTableSize;
  long *m_ShuffleArray;

  KRandomSequencePrivate *d;
};

kdelibs'KRandomSequence::KRandomSequence() (./kdelibs/kdecore/krandomsequence.cpp:30)

KRandomSequence::KRandomSequence( long lngSeed1 )
{
  // Seed the generator
  setSeed( lngSeed1 );
	
	
  // Set the size of the shuffle table
  m_ShuffleArray = new long [m_nShuffleTableSize];
}

kdelibs'KRandomSequence::~KRandomSequence() (./kdelibs/kdecore/krandomsequence.cpp:40)

KRandomSequence::~KRandomSequence()
{
  delete [] m_ShuffleArray;
}


//////////////////////////////////////////////////////////////////////////////
//	Member Functions
//////////////////////////////////////////////////////////////////////////////

kdelibs'KRandomSequence::setSeed() (./kdelibs/kdecore/krandomsequence.cpp:50)

void KRandomSequence::setSeed( long lngSeed1 )
{
  // Convert the positive seed number to a negative one so that the Draw()
  // function can intialise itself the first time it is called. We just have
  // to make sure that the seed used != 0 as zero perpetuates itself in a
  // sequence of random numbers.
  if ( lngSeed1 < 0 )
  {
    m_lngSeed1 = -1;
  }
  else if (lngSeed1 == 0)
  {
    m_lngSeed1 = -KApplication::random();
  }
  else
  {
    m_lngSeed1 = -lngSeed1;
  }
}

kdelibs'KRandomSequence::Draw() (./kdelibs/kdecore/krandomsequence.cpp:73)

void KRandomSequence::Draw()
{
  static const long sMM1            = sMod1 - 1;
  static const long sA1             = 40014;
  static const long sA2             = 40692;
  static const long sQ1             = 53668;
  static const long sQ2             = 52774;
  static const long sR1             = 12211;
  static const long sR2             = 3791;
  static const long sDiv            = 1 + sMM1 / m_nShuffleTableSize;

  // Long period (>2 * 10^18) random number generator of L'Ecuyer with
  // Bayes-Durham shuffle and added safeguards. Returns a uniform random
  // deviate between 0.0 and 1.0 (exclusive of the endpoint values). Call
  // with a negative number to initialize; thereafter, do not alter idum
  // between successive deviates in a sequence. RNMX should approximate
  // the largest floating point value that is less than 1.
	
  int j; // Index for the shuffle table
  long k;
	
  // Initialise
  if ( m_lngSeed1 <= 0 )
  {	
    m_lngSeed2 = m_lngSeed1;

    // Load the shuffle table after 8 warm-ups
    for ( j = m_nShuffleTableSize + 7; j >= 0; j-- )
    {
      k = m_lngSeed1 / sQ1;
      m_lngSeed1 = sA1 * ( m_lngSeed1 - k*sQ1) - k*sR1;
      if ( m_lngSeed1 < 0 )
      {
        m_lngSeed1 += sMod1;
      }
			
      if ( j < m_nShuffleTableSize )
      {
 	m_ShuffleArray[j] = m_lngSeed1;
      }
    }
		
    m_lngShufflePos = m_ShuffleArray[0];
  }
	
  // Start here when not initializing
	
  // Compute m_lngSeed1 = ( lngIA1*m_lngSeed1 ) % lngIM1 without overflows
  // by Schrage's method
  k = m_lngSeed1 / sQ1;
  m_lngSeed1 = sA1 * ( m_lngSeed1 - k*sQ1 ) - k*sR1;
  if ( m_lngSeed1 < 0 )
  {
    m_lngSeed1 += sMod1;
  }
	
  // Compute m_lngSeed2 = ( lngIA2*m_lngSeed2 ) % lngIM2 without overflows
  // by Schrage's method
  k = m_lngSeed2 / sQ2;
  m_lngSeed2 = sA2 * ( m_lngSeed2 - k*sQ2 ) - k*sR2;
  if ( m_lngSeed2 < 0 )
  {
    m_lngSeed2 += sMod2;
  }
	
  j = m_lngShufflePos / sDiv;
  m_lngShufflePos = m_ShuffleArray[j] - m_lngSeed2;
  m_ShuffleArray[j] = m_lngSeed1;
	
  if ( m_lngShufflePos < 1 )
  {
    m_lngShufflePos += sMM1;
  }
}

double

kdelibs'KRandomSequence::getDouble() (./kdelibs/kdecore/krandomsequence.cpp:149)

KRandomSequence::getDouble()
{
  static const double finalAmp         = 1.0 / double( sMod1 );
  static const double epsilon          = 1.2E-7;
  static const double maxRand          = 1.0 - epsilon;
  double temp;
  Draw();
  // Return a value that is not one of the endpoints
  if ( ( temp = finalAmp * m_lngShufflePos ) > maxRand )
  {
    // We don't want to return 1.0
    return maxRand;
  }
  else
  {
    return temp;
  }
}

unsigned long

kdelibs'KRandomSequence::getLong() (./kdelibs/kdecore/krandomsequence.cpp:169)

KRandomSequence::getLong(unsigned long max)
{
  Draw();

  return (((unsigned long) m_lngShufflePos) % max);  
}