package umontreal.iro.lecuyer.randvar;
import umontreal.iro.lecuyer.rng.*;
import umontreal.iro.lecuyer.probdist.*;


/**
 * This class implements random variate generators for
 * the (continuous) uniform distribution over the interval (a, b),
 * where a and b are real numbers with a < b.
 * The density is 
 * 
 * 

 * 

 * f (x) = 1/(b - a)         for a <= x <= b.
 * 

 * 
 * 

 * The (non-static) nextDouble method simply calls inverseF on the
 * distribution.
 * 
 */
public class UniformGen extends RandomVariateGen  {
   private double a;
   private double b;


   /**
    * Creates a uniform random variate generator over the interval
    *   (a, b), using stream s.
    * 
    */
   public UniformGen (RandomStream s, double a, double b)  {
      super (s, new UniformDist(a, b));
      setParams (a, b);
   }


   /**
    * Creates a uniform random variate generator over the interval
    *   (0, 1), using stream s.
    * 
    */
   public UniformGen (RandomStream s)  {
      this (s, 0.0, 1.0);
   }

 
   /**
    * Creates a new generator for the uniform distribution dist
    *    and stream s.
    * 
    */
   public UniformGen (RandomStream s, UniformDist dist)  {
      super (s, dist);
      if (dist != null)
         setParams (dist.getA(), dist.getB());
   }


   /**
    * Generates a uniform random variate over the interval 
    *   (a, b) by inversion, using stream s.
    * 
    */
   static public double nextDouble (RandomStream s, double a, double b)  {
      return UniformDist.inverseF (a, b, s.nextDouble());
   }
      

   /**
    * Returns the value of a for this object.
    * 
    */
   public double getA() {
      return a;
   }
      

   /**
    * Returns the value of b for this object.
    * 
    * 
    */
   public double getB() {
      return b;
   }
      

   /**
    * Sets the value of the parameters a and b for this object.
    * 
    */
   private void setParams (double a, double b) {
      if (b <= a)
         throw new IllegalArgumentException ("b <= a");
      this.a = a;
      this.b = b;
   }
      
}