/*  determine the roots of an equation using iteration  */

#include <stdio.h>

#include <math.h>



#define TRUE  1

#define FALSE 0



void main(void)

{

	int flag = TRUE, count = 0;

	float guess, root, test, error;



	/* read input parameters */

	printf("Initial guess: ");

	scanf("%f",&guess);

	while (flag)  {

		++count;

		if (count == 50 ) flag = FALSE;

		test = 10. - 3. * guess * guess;

		if (test > 0) {

			root = pow(test, 0.2);

			printf("\nIteration number: %2d", count);

			printf("  x= %7.5f", root);

			error = fabs(root - guess);

			if (error > 0.00001) guess = root;  /* repeat calculation   */

			else   {                            /* display final answer */

				flag = FALSE;                   /* error message        */

				printf("\n\nRoot= %7.5f", root);

				printf("  No. of iterations= %2d\n", count);

			}

		}

		else  {

			flag = FALSE;                      /* another error message */

			printf("\nNumbers out of range - try another initial guess");

		}

	}

	if ((count == 50) && (error > 0.00001))

		printf("\n\nConvergence not obtained after 50 iterations");

	getchar();

	getchar();

}