简单的数学到java练习

Question

The assignment is to:

• Create the java statement that will produce f(x) = 2x3 - 8x2 + x + 16.
• Write a Java program that will find the extrema (both high and low) for the function in part 1 across the closed interval (-1, 3).

I don't know what I am doing wrong here exactly but I am getting an infinite number of 9.09.09 and so on.

import java.util.*;
import java.math.*;

public class Extrema
{
   public static void main(String[] args)
   {
      double step = 0.00001;
      double x = -1.0;
      double xn = 3;
      double highest = calc(x);
      while (x <= xn)
      {
         double f = calc(x);
         if (f > highest)
         {
            highest = f;
         }
         step++;
         System.out.print(highest);
      }
   }
   public static double calc(double x)
   {
      double f = 2*Math.pow(x, 1/3) - 8*Math.pow(x, 2) + x + 16;
      return f;
   }
}

Answer 1

Add x+=step at the end of (inside) the while loop.

import java.util.*;
import java.math.*;

public class Extrema
{
   public static void main(String[] args)
   {
      double step = 0.00001;
      double x = -1.0;
      double xn = 3;
      double highest = calc(x);
      while (x <= xn)
      {
         double f = calc(x);
         if (f > highest)
         {
            highest = f;
         }
         x += step;
      }
     System.out.println(highest);
   }
   public static double calc(double x)
   {
      double f = 2*Math.pow(x, 3) - 8*Math.pow(x, 2) + x + 16;
      return f;
   }
}

This outputs: 16.03175629885453 on my system.