#include <stdio.h>
#include <math.h>

// A variable used to initialize the generator (should never be 0).
long r_seed = 12345678L;

// A function that returns a random number between 0 and 1.

double uniform ()
{
  // Constants needed for random generation, not needed anywhere else.
  const static long m = 2147483647L;
  const static long a = 48271L;
  const static long q = 44488L;
  const static long r = 3399L;

  long t, lo, hi;
  double u;

  hi = r_seed / q;
  lo = r_seed - q * hi;
  t = a * lo - r * hi;
  if (t > 0)
    r_seed = t;
  else
    r_seed = t + m;
  u = (double) r_seed / (double) m ;

  return u;
}


void setSeed (long newSeed)
{
  r_seed = newSeed;
}


double uniform_range (double a, double b)
{
  if (b > a) {
    return ( a + (b-a) * uniform() );
  }
  else if (b == a) {
    return a;
  }
  else { 
    printf ("ERROR: in uniform.uniform_range(): a=%lf b=%lf\n", a, b); 
    return 0;
  }
}


int discrete_uniform (int a, int b)
{
  if (b > a) {
    double x = uniform ();
    int c = ( a + (int) floor ((b-a+1)*x) );
    return c;
  }
  else if (a == b) {
   return a;
  }
  else { 
    printf("ERROR in uniform.discrete_uniform(): a=%2ld b=%2ld\n", a, b);
    return 0;
  }
}



int main ()
{
  int i;   
  double u;
  int d;

  setSeed (1);

  printf ("Ten random numbers between 10 and 20:\n");
  for (i=0; i < 10; i++) {
    u = uniform_range (10, 20);
    printf (" %lf\n", u);
  }

  printf ("Ten random integers between 10 and 20:\n");
  for (i=0; i < 10; i++) {
    d = discrete_uniform (10, 20);
    printf (" %d\n", d);
  }

}