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Stochastic Simulation in Java
/*
* Class: UniformGen
* Description: random variate generators for the uniform distribution over the reals
* Environment: Java
* Software: SSJ
* Copyright (C) 2001 Pierre L'Ecuyer and Universite de Montreal
* Organization: DIRO, Universite de Montreal
* @author
* @since
*
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package umontreal.ssj.randvar;
import umontreal.ssj.rng.*;
import umontreal.ssj.probdist.*;
/**
* This class implements random variate generators for the (continuous)
* *uniform* distribution over the interval @f$(a,b)@f$, where @f$a@f$ and
* @f$b@f$ are real numbers with @f$a < b@f$. The density is
* @anchor REF_randvar_UniformGen_eq_funiform
* @f[
* f(x) = 1/(b - a) \qquad\mbox{ for }a\le x\le b. \tag{funiform}
* @f]
* The (non-static) `nextDouble` method simply calls `inverseF` on the
* distribution.
*
*
*
* @ingroup randvar_continuous
*/
public class UniformGen extends RandomVariateGen {
private double a;
private double b;
/**
* Creates a uniform random variate generator over the interval
* @f$(@f$a, b@f$)@f$, 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 @f$(0,
* 1)@f$, 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
* @f$(@f$a, b@f$)@f$ 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 @f$a@f$ for this object.
*/
public double getA() {
return a;
}
/**
* Returns the value of @f$b@f$ for this object.
*/
public double getB() {
return b;
}
/**
* Sets the value of the parameters @f$a@f$ and @f$b@f$ for this
* object.
*/
private void setParams (double a, double b) {
if (b <= a)
throw new IllegalArgumentException ("b <= a");
this.a = a;
this.b = b;
}
}