C program to compute geometric progression

Problem

Write a program to read two numbers, x and n, and then compute the sum of the geometric progression.

1+x+x2+x3+x4+……….+xn

And then, print x,n and sum.

Solution

The solution to compute the geometric progression in C programming language is given below −

Algorithm

Refer an algorithm to compute the geometric progression.

Step 1 − Start

Step 2 − Repeat

Step 3 − Read values for x and n at runtime

Step 4 − If n > 0 then

     Step 4.1: for i = 0 to n do

       Step 4.1.1: sum = sum +pow(x,i)

       Step 4.1.2: i = i+1

     Step 4.2: print x, n and sum

Step 5 − Else

     Step 5.1: print not a valid n value

     Step 5.2: goto repeat (junp to step 2)

Step 6 − End if

Step 7 − Stop

Flowchart

Given below is a flowchart for an algorithm to compute the geometric progression −

Program

Following is the C program to compute the geometric progression −

#include <stdio.h>
#include <conio.h>
#include <math.h>
main(){
   int x,n,sum=0,i;
   start:
   printf("enter the values for x and n:");
   scanf("%d%d",&x,&n);
   if(n>0){
      for(i=0;i<=n;i++){
         sum = sum+pow(x,i);
      }
      printf("The sum of the geometric progression is:%d",sum);
   }
   else{
      printf("not a valid n:%d value",n);
      getch();
      goto start;
   }
}

Output

When the above program is executed, it produces the following result −

enter the values for x and n:4 5
The sum of the geometric progression is:1365