How do I do x x^3 x^5 x^7 x^9? [closed]-CodePudding

This is just a small part of a much larger problem, but I do need to do this. This has to be done using Java for loops. I only have this so far:

public class MyClass {
public static void main(String args[]) {
  System.out.println(calculateExp(3.0));
}

public static double calculateExp(double x) {
 for(int i = 1; i <= 9; i  = 2) { 
         x  = x*x;
 }
 return x;
}

}

Edit: I also can't use any libraries other than the original, meaning I can't use the easy Math.pow().

CodePudding user response：

Java's Math.pow will be useful (documentation)

You also should not be modifying x as you go (since you always want the same number raised to varying powers), but rather have a separate variable to collect the sum.

In the end, it should look something like this:

public class MyClass {
    public static void main(String args[]) {
        System.out.println(calculateExp(3.0));
    }

    public static double calculateExp(double x) {
        double total = 0.0;
        for(int i = 1; i <= 9; i  = 2) {
            total  = Math.pow(x, i);
        }
        return total;
    }
}

EDIT: if you're not allowed to use Math.pow, you can calculate x^i manually with another loop, like this:

public class MyClass {
    public static void main(String args[]) {
        System.out.println(calculateExp(3.0));
    }

    public static double calculateExp(double x) {
        double total = 0.0;
        for(int i = 1; i <= 9; i  = 2) {
            double x_to_i = 1.0;
            for(int j = 0; j < i; j  ) {
                x_to_i *= x;
            }
            total  = x_to_i;
        }
        return total;
    }
}

CodePudding user response：

You can import java.lang.Math, and then use Math.pow(a, b), the code can look like this:

public static void main(String args[])
{
    double a = 30;
    double sum = 0;
    for(int b = 1; b <= 9; b  = 2) { 
        sum  = Math.pow(a, i)
    }
    System.out.println(sum);
}