package umontreal.iro.lecuyer.probdist;


/**
 * This interface should be implemented by all classes supporting 
 * discrete and continuous distributions. It specifies the signature of methods that compute
 * the distribution function F(x),
 * the complementary distribution function bar(F)(x),
 * and the inverse distribution function 
 * F-1(u).
 * It also specifies the signature of methods that returns the mean,
 * the variance and the standard deviation.
 * 
 */
public interface Distribution {

   /**
    * Returns the distribution function F(x).
    * 
    * @param x value at which the distribution function is evaluated
    * 
    *    @return distribution function evaluated at x
    * 
    */
   public double cdf (double x);


   /**
    * Returns 
    * bar(F)(x) = 1 - F(x).
    * 
    * @param x value at which the complementary distribution function is evaluated
    * 
    *  @return complementary distribution function evaluated at x
    * 
    */
   public double barF (double x);


   /**
    * Returns the inverse distribution function
    *    F-1(u), defined in.
    * 
    * @param u value in the interval (0, 1) for which the inverse 
    *      distribution function is evaluated
    * 
    *    @return the inverse distribution function evaluated at u
    * 
    */
   public double inverseF (double u);


   /**
    * Returns the mean of the distribution function.
    * 
    */
   public double getMean();


   /**
    * Returns the variance of the distribution function.
    * 
    */
   public double getVariance();


   /**
    * Returns the standard deviation of the distribution function.
    * 
    */
   public double getStandardDeviation();


   /**
    * Returns the parameters of the distribution function in the same
    *  order as in the constructors.
    * 
    */
   public double[] getParams();

}