/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.commons.math.distribution;

/**
 * The Zipf (or zeta) Distribution.
 * <p>
 * References:
 * <ul>
 * <li><a href="http://mathworld.wolfram.com/ZipfDistribution.html">Zipf
 * Distribution</a></li>
 * </ul>
 * </p>
 * 
 * @version $Revision$ $Date$
 */
public interface ZipfDistribution extends IntegerDistribution {
	/**
	 * Get the number of elements (e.g. corpus size) for the distribution.
	 * 
	 * @return the number of elements
	 */
	public int getNumberOfElements();

	/**
	 * Set the number of elements (e.g. corpus size) for the distribution. The
	 * parameter value must be positive; otherwise an
	 * <code>IllegalArgumentException</code> is thrown.
	 * 
	 * @param n
	 *            the number of elements
	 * @throws IllegalArgumentException
	 *             if n &le; 0
	 */
	public void setNumberOfElements(int n);

	/**
	 * Get the exponent characterising the distribution.
	 * 
	 * @return the exponent
	 */
	public double getExponent();

	/**
	 * Set the exponent characterising the distribution. The parameter value
	 * must be positive; otherwise an <code>IllegalArgumentException</code> is
	 * thrown.
	 * 
	 * @param s
	 *            the exponent
	 * @throws IllegalArgumentException
	 *             if s &le; 0.0
	 */
	public void setExponent(double s);
}