/* random.c - pseudo-random number generators for libbow   Copyright (C) 1998, 1999 Andrew McCallum   Written by:  Andrew Kachites McCallum <mccallum@cs.cmu.edu>   This file is part of the Bag-Of-Words Library, `libbow'.   This library is free software; you can redistribute it and/or   modify it under the terms of the GNU Library General Public License   as published by the Free Software Foundation, version 2.      This library is distributed in the hope that it will be useful,   but WITHOUT ANY WARRANTY; without even the implied warranty of   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU   Library General Public License for more details.   You should have received a copy of the GNU Library General Public   License along with this library; if not, write to the Free Software   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA */#include <bow/libbow.h>#include <stdlib.h>#include <time.h>#include <sys/time.h>#include <unistd.h>/* non-zero if the random number generator is already seeded */static int already_seeded = 0;/* This function seeds the random number generator if needed.  Call   before and random number generator usage, instead of srand */voidbow_random_set_seed (){  if (!already_seeded)    {      if (bow_random_seed == -1)#ifdef HAVE_GETTIMEOFDAY /* for SunOS */	{	  struct timeval tv;	  struct timezone tz;	  	  gettimeofday (&tv, &tz);	  bow_random_seed = tv.tv_usec;	  srandom (bow_random_seed);	}#else        srandom (time (NULL));#endif      else	srandom (bow_random_seed);      already_seeded = 1;    }  return;}/* Set the seed to the same value it had the first time it was set   during this run. */voidbow_random_reset_seed (){  assert (bow_random_seed >= 0);  srandom (bow_random_seed);}/* Return an double between low and high, inclusive */doublebow_random_double (double low, double high){  long r;  double rd;  assert (high - low > 0);  r = random();#if /* 0 && for SunOS */ RAND_MAX  rd = ((double)r) / ((double)RAND_MAX);#elif INT_MAX  rd = ((double)r) / ((double)INT_MAX);#else  rd = ((double)r) / ((double)2147483647);#endif    rd *= (high - low);  rd += low;  return rd;}/* Return an double between 0 and 1, exclusive */doublebow_random_01 (){  double r;  while ((r = bow_random_double (0.0, 1.0)) <= 0.0 || r >= 1.0)    ;  return r;}