/*
 * To parakatw programma ypologizei ena diasthma [a,b] mhkous
 * to poly tol to opoio periexei th riza ths exiswshs f(x)=0,
 * xrhsimopoiwntas th me8odo ths dixotomhshs. To programma
 * ypo8etei oti f(a)f(b) < 0.
*/

#include <stdio.h>

double f(double x)
{
	return -5.0 - x*(2.0 - x*x);
}

int main()
{
	double a = 2.0, b = 3.0, tol = 1.0e-6;
	int    n;
	double h, c, fa, fb, fc;

	h = b - a;
	n = 1;

	fa = f(a);
	fb = f(b);

	while (h > tol) {
		c = (a + b) / 2.0;
		if (c == a || c == b) break;

		fc = f(c);
		if (fc == 0.0) break;

		if (fb * fc < 0) {
			a = c;  fa = fc;
		}
		else {
			b = c;  fb = fc;
		}

		printf("%2d %16.9e %16.9e %16.9e\n", n, c, fc, h);

		h *= 0.5;
	      	n++;
	}

	printf("\nRoot   : %16.9e\n", (a + b)/2.0);
	printf("Length : %16.9e\n", h);

	return 0;
}