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


/**
 * This class implements random variate generators for the
 * noncentral chi square distribution with ν degrees of freedom
 * and noncentrality parameter λ. See the definition in
 *  {@link umontreal.iro.lecuyer.probdist.ChiSquareNoncentralDist ChiSquareNoncentralDist}.
 * 
 */
public class ChiSquareNoncentralGen extends RandomVariateGen  {
   protected double nu = -1.0;
   protected double lambda = -1.0;




   /**
    * Creates a noncentral chi square  random variate generator
    *  with  ν > 0 degrees of freedom and noncentrality parameter λ > 0,
    *  using stream s.
    * 
    */
   public ChiSquareNoncentralGen (RandomStream s, double nu, double lambda)  {
      super (s, new ChiSquareNoncentralDist(nu, lambda));
      setParams (nu, lambda);
   }


   /**
    * Create a new generator for the distribution dist
    *     and stream s.
    * 
    */
   public ChiSquareNoncentralGen (RandomStream s,
                                  ChiSquareNoncentralDist dist)  {
      super (s, dist);
      if (dist != null)
         setParams (dist.getNu (), dist.getLambda());
   }


   /**
    * Generates a new variate from the noncentral chi square
    * distribution with ν degrees of freedom and noncentrality parameter λ,
    *  using stream s.
    * 
    */
   public static double nextDouble (RandomStream s,
                                    double nu, double lambda)  {
      return ChiSquareNoncentralDist.inverseF (nu, lambda, s.nextDouble());
   }



   /**
    * Returns the value of  ν of this object.
    * 
    */
   public double getNu() {
      return nu;
   }


   /**
    * Returns the value of λ for this object.
    * 
    * 
    */
   public double getLambda() {
      return lambda;
   }


   /**
    * Sets the parameters ν = nu and λ =
    *   lambda of this object.
    * 
    */
   protected void setParams (double nu, double lambda) {
      if (nu <= 0.0)
         throw new IllegalArgumentException ("nu <= 0");
      if (lambda < 0.0)
         throw new IllegalArgumentException ("lambda < 0");
      this.nu = nu;
      this.lambda = lambda;
   }

}