# include <stdlib.h>
# include <stdio.h>

double dran01 ( int *seed )
{
  int i4_huge = 2147483647;
  int k;
  double value;

  if ( *seed == 0 )
  {
    printf ( "\n" );
    printf ( "DRAN01 - Fatal error!\n" );
    printf ( "  Input value of SEED = 0.\n" );
    exit ( 1 );
  }
  k = *seed / 127773;

  *seed = 16807 * ( *seed - k * 127773 ) - k * 2836;

  if ( *seed < 0 )
  {
    *seed = *seed + i4_huge;
  }
  value = ( double ) ( *seed ) * 4.656612875E-10;

  return value;
}