Java中对数似然函数的最大化

Question

因此，我为Poisson分布定义了对数似然函数，我想知道是否有一种方法可以在Java中优化（最大化或最小化）该对数似然函数，目前我正在使用NetBeans，而我是新手Java。 这是我的代码：

 package javaapplication1;

 public class JavaApplication1 {


 public static void main(String[] args) {
    // x_input generated from Poisson(3)
    double x_input[]={3,0,4,3,4,4,3,2,3,0};
    // x_input generated from Poisson(3)

    //Initializing Poisson's lamda value 
    double theta_input[]={3};
    //Initializing Poisson's lamda value 

    //Just checking if the functions are well defined
    System.out.println(factorial(3));
    System.out.println(poisson_pdf(3,3));
    System.out.println(poisson_loglik(theta_input,x_input));
    //Just checking if the functions are well defined

}


//   Defining function to compute the factorial 
    public static  double factorial(double n){
      double sum=0;
      for (double i=1; i<=n; i++) sum=sum+Math.log(i);
      return Math.exp(sum);
   }
//   Defining function to compute the factorial 

//   Defining the poisson pdf   
     public static  double poisson_pdf(double x, double lamda){
       return (1/factorial(x)) * (Math.pow(lamda,x)) * (Math.exp(-lamda) ) ;
}
//   Defining the poisson pdf 

//   Defining the poisson loglikelihood which I want to optimize somehow
     public static double poisson_loglik(double theta[], double x[]){
       double lamda_pois=theta[0];
       double loglik_result=0;
       for(int i=0;i<x.length;i++) loglik_result=Math.log(poisson_pdf(x[i],lamda_pois))+loglik_result;
       return loglik_result;
}
//   Defining the poisson loglikelihood which I want to optimize somehow  
}