﻿ C# - Calculate the sum of the series [ 1-X^2/2!+X^4/4!- ...]

# C#: Calculate the sum of the series [ 1-X^2/2!+X^4/4!- .........]

## C# Sharp For Loop: Exercise-18 with Solution

Write a program in C# Sharp to find the sum of the series [ 1-X^2/2!+X^4/4!- .........].

Sample Solution:

C# Sharp Code:

``````using System;  // Importing necessary namespace

public class Exercise18  // Declaration of the Exercise18 class
{
public static void Main()  // Main method, entry point of the program
{
double x, sum, t, d;  // Declaration of variables of type double
int i, n;  // Declaration of variables of type integer

Console.Write("\n\n");  // Displaying new lines
Console.Write("Calculate the sum of the series [ 1-X^2/2!+X^4/4!- .........]:\n");  // Displaying the purpose of the program
Console.Write("----------------------------------------------------------------");  // Displaying a separator
Console.Write("\n\n");

Console.Write("Input the Value of x :");  // Prompting the user to input the value of x
x = Convert.ToInt32(Console.ReadLine());  // Reading the value of x entered by the user

Console.Write("Input the number of terms : ");  // Prompting the user to input the number of terms
n = Convert.ToInt32(Console.ReadLine());  // Reading the number of terms entered by the user

sum = 1;  // Initializing the sum to 1 (as the series starts with 1)
t = 1;  // Initializing t to 1 (initial term)

// Loop to calculate the sum of the series
for (i = 1; i < n; i++)
{
d = (2 * i) * (2 * i - 1);  // Calculation of denominator value (factorial)
t = -t * x * x / d;  // Calculation of the current term in the series
sum = sum + t;  // Adding the current term to the sum
}

// Displaying the calculated sum, number of terms, and value of x
Console.Write("\nThe sum = {0}\nNumber of terms = {1}\nValue of x = {2}\n", sum, n, x);
}
}
```
```

Sample Output:

```Calculate the sum of the series [ 1-X^2/2!+X^4/4!- .........]:
----------------------------------------------------------------
Input the Value of x :5
Input the number of terms : 2
the sum = -11.5
Number of terms = 2
value of x = 5
```

Flowchart:

C# Sharp Code Editor: