Numeric Integration in Java

Question

I need your help again.

I need to know how I can send any functions to my class in order that my method works.

For example, in the code below, I can send only log function. But I would like to send any expressions as a function. Did I clear?

Thanks everyone for helping.

The class: package appMatematica;

import java.util.*;

public class Simpsons13 {

    // Given function to be integrated
      // Function to calculate f(x)
    static float func(float x)
    {
        return (float)Math.log(x);
    }
 
    // Function for approximate integral
    static float simpsons13(float ll, float ul,
                                       int n)
    {
        // Calculating the value of h
        float h = (ul - ll) / n;
 
        // Array for storing value of x
        // and f(x)
        float[] x = new float[10];
        float[] fx= new float[10];
 
        // Calculating values of x and f(x)
        for (int i = 0; i <= n; i++) {
            x[i] = ll + i * h;
            fx[i] = func(x[i]);
        }
 
        // Calculating result
        float res = 0;
        for (int i = 0; i <= n; i++) {
            if (i == 0 || i == n)
                res += fx[i];
            else if (i % 2 != 0)
                res += 4 * fx[i];
            else
                res += 2 * fx[i];
        }
         
        res = res * (h / 3);
        return res;
    }
}

THE MAIN:

package appMatematica;

import java.util.Scanner;
import appMatematica.Gauss;
import appMatematica.Simpsons38;
import appMatematica.Trapezios;

public class Principal {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int op = 0;

        System.out.println("Escolha qual operação quer realizar\n");
        System.out.println("1-Trapézios \n2-Simpsons 3/8 \n3-Simpsons 1/3 \n4-Quadratura de GAUSS");
        op = sc.nextInt();

        if (op == 1) {

            double x1;
            double x2;
            int i;
            System.out.println("Digite o valor de x1\n");
            x1 = sc.nextDouble();
            System.out.println("Digite o valor de x2\n");
            x2 = sc.nextDouble();
            System.out.println("Digite o valor do intervalo\n");
            i = sc.nextInt();
            System.out.println(Trapezios.trapezio(x1, x2, i));

        }

        if (op == 2) {

            float limite_inferior;
            float limite_superior;
            int i;

            System.out.println("Digite o limite inferior\n");
            limite_inferior = sc.nextFloat();
            System.out.println("Digite o limite superior\n");
            limite_superior = sc.nextFloat();
            System.out.println("Digite o número de iterações\n");
            i = sc.nextInt();

            System.out.println(Simpsons38.calculate38(limite_inferior, limite_superior, i));

        }

        if (op == 3) {

            float limite_inferior;
            float limite_superior;
            int i;

            System.out.println("Digite o limite inferior\n");
            limite_inferior = sc.nextFloat();
            System.out.println("Digite o limite superior\n");
            limite_superior = sc.nextFloat();
            System.out.println("Digite o número de iterações\n");
            i = sc.nextInt();

            System.out.println(Simpsons13.simpsons13(limite_inferior, limite_superior, i));

        }

    }

}