Math pow Java | The Math pow() method in Java

Introduction to Math pow Java, in this tutorial you will learn how to use math pow in Java?

java.lang.Math.pow() in java is a very commonly used method. It takes in 2 parameters a and b and returns a raised to power b.

Syntax of java math pow method

Math.pow(a,b)

Example 1 : Math pow java code

For instance, here’s a java code to take two numbers a and b, and print a raised to power b.

public class MathPow {
	public static void main(String[] args) {
		int a = 2;
		int b = 2;
		double ans = Math.pow(a,b);
		System.out.println(a+" raised to power "+b+" is "+ans);
	}
}

Output

2 raised to power 2 is 4.0

That’s it.

A simple method with lots of uses.

Available at java.lang package, the Math class has more methods to help in mathematical and arithmetical operations. Math.floor(), Math.round(), Math.ceil(), Math.acos(), Math.asin(), many more.

That’s a story for another day, now let’s analyse another interesting example of Math.pow().

Example 2

Now, try to guess the output of the following code snippet.

public class MathPow {
	public static void main(String[] args) {
		char a = 'd';
		int b = 2;
		double ans = Math.pow(a,b);
		System.out.println(a+" raised to power "+b+" is "+ans);
	}
}

Well, the answer lies in the fact that the ASCII value for (a-z) is (97-122).

Similarly, (A-Z) is (65-90). So, probably you have guessed already that the answer will be the ASCII value of ‘d’ raised to power 2.

However, it is quite unusual for one to use characters in this scenario.

Still, it gives an understanding that java can cast characters to an integer with their ASCII values automatically.

Example 3

In the shell, what we are doing here with Math.pow() is called Exponentiation.

It is a Mathematical operation involving 2 numbers- base b and exponent e. (b^e) Read as b “raised to power” e.

Basically, we multiply the base with itself ‘e’ times. But if e is 0, no matter what is the value of the base, the result will be 1. Anything raised to power 0 is 1.

Math.pow(2,0)

Value
1.0

Example 4

Now let’s try to calculate 2^(2^2). The answer should be 16. (2^4).
Here’s the code for help.

public class MathPow {
	public static void main(String[] args) {
		int a = 2;
		int b = 2;
		int c = 2;
		double ans = Math.pow(a,Math.pow(b,c));
		System.out.println(a+" raised to power "+b+" raised to power "+c+" is "+ans);
	}
}

Output

2 raised to power 2 raised to power 2 is 16.0

Math.pow() java Exercise

If you have come so far, here’s an exercise for you. Try to create a method called power(base,exp), and return base raised to power exp.

If implemented properly it should behave the same as the Math.pow() method.

Great if you tried! Now let’s look at the solution.

public class MathPow {
	static double power(int base, int exp) { // returns base^exp
		if(exp == 0) { //zero exponent rule
			return 1;
		}
		else if(exp > 0) { //for positive power
			return base*power(base, exp-1);
		}
		else if(exp < 0) { //for negative power
			return (1.0/base)*power(base, exp+1);
		}
		return 0; // no use but need to mention to avoid a compilation error.
	}
	public static void main(String[] args) {
		int a = 2; // base
		int b = -2; // exponent
		double result = power(a,b);
		System.out.printf("%d raised to power %d is %.2f  ",a,b,result);
/***simple if-else code to compare with java.lang.Math.pow()***/
		if(power(a,b) == Math.pow(a, b))
			System.out.println("***Correct Answer***");
		else
			System.out.println("***Wrong Answer***");
	}
}

We have used simple recursion to create the power() method.

First, we check if the exponent is 0. If so, we return 1.

Otherwise, we check if the exponent is greater than 0. If so, we make a recursive call to power() methodreturn base*power(base, exp-1); with exp value reduced by 1 and multiply the base with it.

Else, the exponent must be negative. Therefore you can replace else if(exp < 0) { with else and the code will work same.

In this case, we have to return (1.0/base)*power(base, exp+1). The ‘1.0’ is important! If replaced by ‘1’ the expression will be treated as an integer and the value will likely become 0.

Since the exponent is negative be sure to increase it by 1 in the recursive call.
Lastly, we have compared the results with that of Math.pow(). If same, we print “Correct”, “Wrong” if not.

Output

2 raised to power -2 is 0.25  ***Correct Answer***

You can check out How to do Exponents in Java?

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