Consider again the following series 1 Sigmak infinity k1 1k

Consider again the following series: 1+ Sigma^k = infinity _k=1 (-1)^k * (x/2)^2k/(k!)^2 For x = 1.5 write a VBA program to evaluate this series. Use a Do While loop to continue the summation until the magnitude of a term is less than 0.5EE-7 or 20 summation terms are computed. Handle input and output in the main sub. Evaluate the series in a subordinate sub. Evaluate k! in a user-defined function using a for loop. Output the value of your series, the last term computed, and the last value of k used.

Solution

The VB Code

Imports System.Collections.Generic
Imports System.Text
Imports System.Threading.Tasks

Namespace ConsoleApplication3
   Class Program
       Private Shared Sub Main(args As String())
           Dim a As Double = 5E-07
           Dim counter As Integer = 0, k As Integer = 0
           Dim sum As Double = 0.0
           Dim x As Double = 1.5
           Do
               Dim factK As Long = fact(k)
               sum = sum + (Math.Pow(-1, k) * (Math.Pow((x / 2), (2 * k)))) / Math.Pow(factK, 2)
               counter += 1
               k += 1
           Loop While sum > a AndAlso counter < 21
           Console.WriteLine(sum)
           Console.ReadLine()

       End Sub

       Private Shared Function fact(k As Integer) As Long
           Dim facto As Long = 1
           For i As Integer = 1 To k
               fact = fact * i
           Next
           Return fact
       End Function
   End Class
End Namespace

The logic is successfully implemented in above code. but there might be some compiler error like No accessible \'Main\' method with an appropriate signature was found in \'ConsoleApplication5\'.   ConsoleApplication5 . Just correct them accordingly for your Visual studio.

The C# code also for the same

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication3
{
class Program
{
static void Main(string[] args)
{
double a = 0.0000005;
int counter = 0,k=0;
double sum = 0.0;
double x = 1.5;
do
{
long factK = fact(k);
sum = sum + (Math.Pow(-1, k) * (Math.Pow((x / 2), (2 * k)))) / Math.Pow(factK, 2);
counter++;
k++;
} while (sum > a && counter < 21);
Console.WriteLine(sum);
Console.ReadLine();

}

private static long fact(int k)
{
long fact = 1;
for(int i=1;i<=k;i++)
{
fact = fact * i;
}
return fact;
}
}
}

It will run perfectly fine.