random.cpp

Ball Vector Machine (BVM)支撑向量机C++程序项目代码

static int rand_type = TYPE_3;

static int rand_deg = DEG_3;

static int rand_sep = SEP_3;


static long int *end_ptr = &randtbl[sizeof (randtbl) / sizeof (randtbl[0])];

  
/* Initialize the random number generator based on the given seed.  If the
   type is the trivial no-state-information type, just remember the seed.
   Otherwise, initializes state[] based on the given "seed" via a linear
   congruential generator.  Then, the pointers are set to known locations
   that are exactly rand_sep places apart.  Lastly, it cycles the state
   information a given number of times to get rid of any initial dependencies
   introduced by the L.C.R.N.G.  Note that the initialization of randtbl[]
   for default usage relies on values produced by this routine.  */ 

void srandom (unsigned int x) 
{
    state[0] = x;
    if (rand_type != TYPE_0)
    {
        register long int i;
        for (i = 1; i < rand_deg; ++i)
        state[i] = (1103515145 * state[i - 1]) + 12345;
        fptr = &state[rand_sep];
        rptr = &state[0];
        for (i = 0; i < 10 * rand_deg; ++i)
        random ();
    }
}


/* Initialize the state information in the given array of N bytes for
   future random number generation.  Based on the number of bytes we
   are given, and the break values for the different R.N.G.'s, we choose
   the best (largest) one we can and set things up for it.  srandom is
   then called to initialize the state information.  Note that on return
   from srandom, we set state[-1] to be the type multiplexed with the current
   value of the rear pointer; this is so successive calls to initstate won't
   lose this information and will be able to restart with setstate.
   Note: The first thing we do is save the current state, if any, just like
   setstate so that it doesn't matter when initstate is called.
   Returns a pointer to the old state.  */ 

PTR initstate (unsigned int seed, PTR arg_state, unsigned long n) 
{
	PTR ostate = (PTR) & state[-1];
	if (rand_type == TYPE_0)
		state[-1] = rand_type;
	else    
		state[-1] = (MAX_TYPES * (rptr - state)) + rand_type;
	  
	if (n < BREAK_1) {
		if (n < BREAK_0) {
			errno = EINVAL;
			return (char*) NULL;
		}
		rand_type = TYPE_0;
		rand_deg = DEG_0;
		rand_sep = SEP_0;
	}
	else if (n < BREAK_2)    
	{      
		rand_type = TYPE_1;
		rand_deg = DEG_1;
		rand_sep = SEP_1;
	}
	  
	else if (n < BREAK_3)
	{
		rand_type = TYPE_2;
		rand_deg = DEG_2;
		rand_sep = SEP_2;
	}
	  
	else if (n < BREAK_4)
	{      
		rand_type = TYPE_3;
		rand_deg = DEG_3;
		rand_sep = SEP_3;
	}	  
	else
	{
		rand_type = TYPE_4;
		rand_deg = DEG_4;
		rand_sep = SEP_4;
	}
	  
	state = &((long int *) arg_state)[1];       /* First location.  */
	  
	/* Must set END_PTR before srandom.  */ 
	end_ptr = &state[rand_deg];
	  
	srandom (seed);
	  
	if (rand_type == TYPE_0)
		state[-1] = rand_type;
	else    
		state[-1] = (MAX_TYPES * (rptr - state)) + rand_type;  

	return ostate;

}


/* Restore the state from the given state array.
   Note: It is important that we also remember the locations of the pointers
   in the current state information, and restore the locations of the pointers
   from the old state information.  This is done by multiplexing the pointer
   location into the zeroeth word of the state information. Note that due
   to the order in which things are done, it is OK to call setstate with the
   same state as the current state
   Returns a pointer to the old state information.  */ 
  
PTR setstate (PTR arg_state) 
{
  
	register long int *new_state = (long int *) arg_state;
	register int type = new_state[0] % MAX_TYPES;
	register int rear = new_state[0] / MAX_TYPES;
	PTR ostate = (PTR) & state[-1];

	if (rand_type == TYPE_0)    
		state[-1] = rand_type;
	else
		state[-1] = (MAX_TYPES * (rptr - state)) + rand_type;
	  
	switch (type) {
	case TYPE_0:
	case TYPE_1:
	case TYPE_2:
	case TYPE_3:
	case TYPE_4:
		rand_type = type;
		rand_deg = degrees[type];
		rand_sep = seps[type];
		break;

	default:      
		/* State info munged.  */ 
		errno = EINVAL;
	      
		return  (char*)NULL;    
	}
	  
	state = &new_state[1];
	  
	if (rand_type != TYPE_0)
	{
		rptr = &state[rear];
		fptr = &state[(rear + rand_sep) % rand_deg];
	}
	  
	/* Set end_ptr too.  */ 
	end_ptr = &state[rand_deg];

	return ostate;
}


  
/* If we are using the trivial TYPE_0 R.N.G., just do the old linear
   congruential bit.  Otherwise, we do our fancy trinomial stuff, which is the
   same in all ther other cases due to all the global variables that have been
   set up.  The basic operation is to add the number at the rear pointer into
   the one at the front pointer.  Then both pointers are advanced to the next
   location cyclically in the table.  The value returned is the sum generated,
   reduced to 31 bits by throwing away the "least random" low bit.
   Note: The code takes advantage of the fact that both the front and
   rear pointers can't wrap on the same call by not testing the rear
   pointer if the front one has wrapped.  Returns a 31-bit random number.  */ 

long int random () 
{
  
	if (rand_type == TYPE_0)
	{
		state[0] = ((state[0] * 1103515245) + 12345) & LONG_MAX;
		return state[0];
	}
	else    
	{
		long int i;
		      
		*fptr += *rptr;
		      
		/* Chucking least random bit.  */ 
		i = (*fptr >> 1) & LONG_MAX;
		      
		++fptr;
		      
		if (fptr >= end_ptr)	        
		{
			fptr = state;
			++rptr;        
		}
		else        
		{          
			++rptr;
			if (rptr >= end_ptr)	            
				rptr = state;	        
		}
		return i;
	}
}