Question

How to check if a sequence of numbers is a Harmonic progression (reciprocals Arithmetic progression) in C#

Answer 1

using System;

// a, b, c, d are HP if 1/a, 1/b, 1/c, 1/d are AP -> 1/a, 1/(a+diff), 1/(a+2*diff)...

public class SequenceIsHarmonicProgression_CSharp
{
	public static int isHarmonicProgression(double[] arr)
	{
		int size = arr.Length;
		if (size == 1) {
			return 1;
		}

		double difference = (1.0 / arr[1]) - (1.0 / arr[0]);

		for (int i = 2; i < size; i++) {
			if ((1.0 / arr[i]) - (1.0 / arr[i - 1]) != difference) {
				return 0;
			}
		}

		return 1;
	}

	public static void Main(string[] args)
	{
		double[] arr = new double[] {1.0 / 5, 1.0 / 10, 1.0 / 15, 1.0 / 20, 1.0 / 25};

		Console.WriteLine(isHarmonicProgression(arr) == 1 ? "Yes" : "No");
	}
}



/*
run:

Yes

*/

 

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