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


/**
 * This class implements random variate generators for the 
 *  hyperbolic secant distribution with location
 *  parameter μ and scale parameter σ.
 * The density function of this distribution is
 * 
 * 

 * 

 * f (x) = 1/(2σ) sech(π/2(x - μ)/σ),         - ∞ < x < ∞.
 * 

 * 
 */
public class HyperbolicSecantGen extends RandomVariateGen  {
   protected double mu;
   protected double sigma;




   /**
    * Creates a hyperbolic secant random variate generator
    *   with parameters μ = mu and σ = sigma,
    *   using stream s.
    * 
    */
   public HyperbolicSecantGen (RandomStream s, double mu, double sigma)  {
      super (s, new HyperbolicSecantDist(mu, sigma));
      setParams (mu, sigma);
   }


   /**
    * Creates a hyperbolic secant random variate generator
    *   with parameters μ = 0 and σ = 1,
    *   using stream s.
    * 
    */
   public HyperbolicSecantGen (RandomStream s)  {
      this (s, 0.0, 1.0);
   }


   /**
    * Creates a new generator for the distribution dist,
    *      using stream s.
    * 
    */
   public HyperbolicSecantGen (RandomStream s, HyperbolicSecantDist dist)  {
      super (s, dist);
      if (dist != null)
         setParams (dist.getMu(), dist.getSigma());
   }


   /**
    * Generates a variate from the hyperbolic secant distribution with
    *    location parameter μ and scale parameter σ.
    * 
    */
   public static double nextDouble (RandomStream s, double mu, double sigma) {
      return HyperbolicSecantDist.inverseF (mu, sigma, s.nextDouble());
   }


   /**
    * Returns the parameter μ of this object.
    * 
    */
   public double getMu() {
      return mu;
   }


   /**
    * Returns the parameter σ of this object.
    * 
    * 
    */
   public double getSigma() {
      return sigma;
   }


   /**
    * Sets the parameters μ and σ of this object.
    * 
    */
   protected void setParams (double mu, double sigma) {
      if (sigma <= 0.0)
         throw new IllegalArgumentException ("sigma <= 0");
      this.mu = mu;
      this.sigma = sigma;
   }

}