Approximate Nth Prime - CSharp System

CSharp examples for System:Math Number

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Description

Approximate Nth Prime

Demo Code


using System.Numerics;
using System.Collections.Generic;
using System.Collections;
using System;//from  w w  w .  j  a  va2 s .  co m
using EulersSolver.Extensions;

public class Main{
        public static int ApproximateNthPrime(int nn)
        {
            double n = (double)nn;
            double p;
            if (nn >= 7022)
            {
                p = n * Math.Log(n) + n * (Math.Log(Math.Log(n)) - 0.9385);
            }
            else if (nn >= 6)
            {
                p = n * Math.Log(n) + n * Math.Log(Math.Log(n));
            }
            else if (nn > 0)
            {
                p = new int[] { 2, 3, 5, 7, 11 }[nn - 1];
            }
            else
            {
                p = 0;
            }
            return (int)p;
        }
}

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