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 * Copyright (c) 2010-2020 Haifeng Li. All rights reserved.
 *
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package smile.stat.distribution;

/**
 * The purpose of this interface is mainly to define the method M that is
 * the Maximization step in the EM algorithm. Note that distributions of exponential
 * family has the close-form solutions in the EM algorithm. With this interface,
 * we may allow the mixture contains distributions of different form as long as
 * it is from exponential family.
 *
 * @see ExponentialFamilyMixture
 * @see DiscreteExponentialFamilyMixture
*
 * @author Haifeng Li
 */
public interface DiscreteExponentialFamily {

    /**
     * The M step in the EM algorithm, which depends the specific distribution.
     *
     * @param x the input data for estimation
     * @param posteriori the posteriori probability.
     * @return the (unnormalized) weight of this distribution in the mixture.
     */
    DiscreteMixture.Component M(int[] x , double[] posteriori);
}