# Finding Sum of ln(1+x) Using Recursive Function

This program calculates sum of series `ln(1+x)` up to `n`

terms using recursion in C programming language.

## Program

```
#include<stdio.h>
#include<conio.h>
#include<math.h>
/* Function prototype */
float logfun(float x, int n);
/* Main Function */
int main()
{
float x, result;
int n;
clrscr();
printf("Enter value of x:\n");
scanf("%f", &x);
printf("Enter number of terms:\n");
scanf("%d", &n);
/* Function Call */
result = logfun(x,n);
printf("ln(1+%0.2f) = %0.4f", x, result);
getch();
return 0;
}
/* Function Definition */
float logfun(float x, int n)
{
if(n< 0)
{
return 0;
}
else
{
return pow(-1, n) * pow(x, n+1)/(n+1) + logfun(x,n-1); /* Recursive function */
}
}
```

## Output

Enter value of x: 0.5 ↲ Enter number of terms: 10 ↲ ln(1+0.50) = 0.4055 Note: ↲ indicates ENTER is pressed.