#define IA 16807#define IM 2147483647#define AM (1.0/IM)#define IQ 127773#define IR 2836#define MASK 123459876float ran0(long &idum)// "Minimal" random number generator of Park and Miller with// Bays-Durham shuffle and added safeguards. Returns a uniform random// deviate between 0.0 and 1.0. Set or reset idum to any integer value// (except the unlikely value MASK) to initialize the sequence; idum// must not be altered between calls for successive deviates in a sequence. {  long k;  float ans;    idum ^= MASK;			  // XORing with MASK allows use of 0 and  k = idum/IQ;			  //     other simple bit patterns for idum.  idum = IA * (idum-k*IQ) - IR*k; // Compute idum = (IA*idum) % IM without  if (idum < 0) idum += IM;	  //     overflows by Schrage's method.  ans = AM * idum;		  // Convert idum to a floating result.  idum ^= MASK;			  // Unmask before return.  return ans;}