# Fixed Point Iteration Method Using C with Output

Earlier in Fixed Point Iteration Method Algorithm and Fixed Point Iteration Method Pseudocode , we discussed about an algorithm and pseudocode for computing real root of non-linear equation using Fixed Point Iteration Method. In this tutorial we are going to implement this method using C programming language.

## Complete Program for Fixed Point Iteration Method using C Programming Language

``````
/* Program: Finding real roots of nonlinear
equation using Fixed Point Iteration
Author: CodeSansar
Date: November 18, 2018 */
#include<stdio.h>
#include<conio.h>
#include<math.h>

/* Define function f(x) which
is to be solved */
#define   f(x)   cos(x)-3*x+1
/* Write f(x) as x = g(x) and
define g(x) here */
#define   g(x)   (1+cos(x))/3

int main()
{
int step=1, N;
float x0, x1, e;
clrscr();
/* Inputs */
printf("Enter initial guess: ");
scanf("%f", &x0);
printf("Enter tolerable error: ");
scanf("%f", &e);
printf("Enter maximum iteration: ");
scanf("%d", &N);
/* Implementing Fixed Point Iteration */
printf("\nStep\tx0\t\tf(x0)\t\tx1\t\tf(x1)\n");
do
{
x1 = g(x0);
printf("%d\t%f\t%f\t%f\t%f\n",step, x0, f(x0), x1, f(x1));

step = step + 1;

if(step>N)
{
printf("Not Convergent.");
exit(0);
}

x0 = x1;

}while( fabs(f(x1)) > e);

printf("\nRoot is %f", x1);

getch();
return(0);
}
``````

## Output: Fixed Point Iteration Using C

```Enter initial guess: 1
Enter tolerable error: 0.000001
Enter maximum iteration: 10

Step    x0              f(x0)           x1              f(x1)
1       1.000000        -1.459698       0.513434        0.330761
2       0.513434        0.330761        0.623688        -0.059333
3       0.623688        -0.059333       0.603910        0.011391
4       0.603910        0.011391        0.607707        -0.002162
5       0.607707        -0.002162       0.606986        0.000411
6       0.606986        0.000411        0.607124        -0.000078
7       0.607124        -0.000078       0.607098        0.000015
8       0.607098        0.000015        0.607102        -0.000003
9       0.607102        -0.000003       0.607102        0.000001

Root is 0.607102
```