Algorithm based on the random generation of Poissonian numbers, based on Knuth and Numerical Recipes (7.3.12). - Java java.lang

Java examples for java.lang:Math Number

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Description

Algorithm based on the random generation of Poissonian numbers, based on Knuth and Numerical Recipes (7.3.12).

Demo Code


//package com.java2s;

public class Main {
    /**/*from w ww. j a v a2  s . c  o m*/
     * Algorithm based on the random generation of Poissonian numbers,
     * based on Knuth and Numerical Recipes (7.3.12).
     * 
     * In the sources above, prob is actually a uniform random number 
     * between 0-1, sampled each iteration. I have to make sure that 
     * my alteration for a fixed value (to replace gene values) is 
     * correct...
     * 
     * @param lambda
     * @return
     */
    static public int getPoisson(double prob, double lambda) {
        double L = Math.exp(-lambda);
        int k = 0;
        double p = 1;

        do {
            k++;
            p = p * prob;
        } while (p > L);

        // The original algorithm has k-1. We remove the -1 to guarantee
        // at least 1 event for every bin.
        return k;
    }
}

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