Calculate Pi (π) using Leibniz formula

problem

It is pi day and you wish to write some code in your favorite language to calculate its value. You can pick Leibniz’s formula and implement it in Kotlin.

Recall the Leibniz formula:

piCalculation

SOLUTION

The series above can be implemented as follow (one solution):

Pi.kt
				
					fun calculatePi(): Double {

    var index = 0
    var pi = 0.0
    var denominator = 1
    val iterations = 1000000

    while (index < iterations) {

        if (index % 2 == 0)
            pi += 4.0 / denominator
        else
            pi -= 4.0 / denominator

        index += 1
        denominator += 2
    }

    return pi;
}
				
			

Iterating the above 1M times will give the constant pi number.

running
Putting a Kotlin main function
Pi.kt
				
					fun main() {
        println(calculatePi())
}

fun calculatePi(): Double {

    var index = 0
    var pi = 0.0
    var denominator = 1
    val iterations = 1000000

    while (index < iterations) {

        if (index % 2 == 0)
            pi += 4.0 / denominator
        else
            pi -= 4.0 / denominator

        index += 1
        denominator += 2
    }

    return pi;
}
				
			

We can either copy & paste the code above into our Kotlin IDE or use the online Kotlin playground

COMPILE AND RUN

By using the terminal we can also compile it with kotlin compiler as follows:

				
					kotlinc Pi.kt
				
			

the above will generate PiKt.class file that is to be executed as follows:

				
					kotlin PiKt
				
			
output
				
					3.1415916535897743
				
			

Looks correct!

conclusion

In this post we saw how to calculate the constant PI number by using a simple implementation of the Leibniz formula in Kotlin.

References:

 

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Ellion

Professional IT consultant, writer, programmer enthusiast interested in all sorts of coding.
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