Scala: How to square a number (Int, Double, Float, Long)

Scala math FAQ: How do I square a number in Scala, such as squaring an Int, Double, Long, or Float?

Solution

You can square a number in Scala in at least 2-3 different ways:

1. Multiply the number by itself
2. Call the Java Math.pow function or the scala.math.pow function

The following examples demonstrate these solutions.

NOTE: If you want to square a number in Java, you can also use the first two solutions I use below.

1) Scala: Square a number by multiplying it by itself

This is how you square a number in Scala by multiplying it by itself:

val i = 2
val square = i * i

In this example if you print the value of square, it will be 4. An important point to know about this solution is that if you are squaring an integer in Scala, such as the number 2, the result will also be an Int, in this case the value 4. You can use the same technique with Int, Double, Long, and Float.

2) Scala: Square a number with the Math.pow method

Here’s how you call the Math.pow or scala.math.pow methods to square a number:

// Math.pow
val i = 2
val square = Math.pow(i, 2)     // '2' means "square"

// scala.math.pow
val i = 2
val square = scala.math.pow(i, 2)

An important point to know about this solution is that if you square an integer, the result will actually be a Double, so you’ll need to convert it back to an Int or a Long, if you want those types.

More details

The Scala version of pow is a function in the scala.math package object, as you can see in that Scaladoc. If you dig into the scala.math.pow source code, you’ll see that it’s defined like this:

def pow(x: Double, y: Double): Double = java.lang.Math.pow(x, y)

Therefore, if you prefer, when squaring numbers you can call Math.pow — which is java.lang.Math.pow, because java.lang.* is imported by default — directly, if you’d like to save a layer of abstraction.

Note that because the pow function takes a Double as its input parameter, you can pass in a Double, Int, Float, or Long.

Bonus: More Scala power multipliers

In general I just multiply the number by itself to get the squared value, but the advantage of the Math.pow method is that once you know how to use it, you can cube a number and use other powers of multiplication like this:

val i = 2
val j = Math.pow(i, 2)  // square (to the power of 2)
val k = Math.pow(i, 3)  // to the power of 3
val l = Math.pow(i, 4)  // to the power of 4

As mentioned earlier, the disadvantage of this approach is that if you want to work with integers, the result of the pow functions is a Double, so if you want an Int or Long as the end result, you’ll have to convert that Double back to an Int or Long.

Bonus: How to convert from a Double to an Int (or Long)

Note that if you want to convert a Double to an Int, the correct solution is to test the Double value to make sure it can be properly converted to an Int. Do this with the isValidInt function, as shown in these Scala REPL examples:

scala> 9.9.isValidInt
val res0: Boolean = false
                                                                                                    
scala> 9.0.isValidInt
val res1: Boolean = true

As shown in those examples, the Double value 9.9 cannot be converted to an Int, but 9.0 can be converted to an Int.

In a slightly-related note, functions like ceil (ceiling), floor, round, isWhole, and longValue can also help when you want to convert a Double value to an Int or Long:

scala> 9.9.ceil
val res2: Double = 10.0
                                                                                                    
scala> 9.9.floor
val res3: Double = 9.0
                                                                                                    
scala> 9.9.round
val res4: Long = 10
                                                                                                    
scala> 9.9.isWhole
val res5: Boolean = false
                                                                                                    
scala> 9.9.longValue
val res6: Long = 9

Summary: How to square a number in Scala

In summary, if you wanted to see a few ways to square a number (Int, Double, Float, or Long) in Scala, I hope these examples are helpful.