/*
 * Program to find real roots of quadratic equation, using a function.
 * Also prints some "test case" examples.
 */
#include <stdio.h>
#include <math.h>

void print_real_roots(double a, double b, double c);

int main(void) {
	/* try to come up with one test for each condition in function code */
	print_real_roots(1, 0, -1);
	print_real_roots(1, -4, 4);
	print_real_roots(1, 0, 1);
	print_real_roots(0, 2, 1);
	print_real_roots(0, 0, 1);
	print_real_roots(0, 0, 0);

	printf("enter coefficients a, b, c\n");
	double a, b, c;
	if (scanf("%lf %lf %lf", &a, &b, &c) != 3) {
		printf("invalid input\n");
		return 1; /* bail out of program */
	}

	print_real_roots(a, b, c);
	return 0;

}

void print_real_roots(double a, double b, double c) {
	printf("finding roots for a = %f, b = %f, c = %f\n", a, b, c);

	double d = b*b - 4*a*c;
	if (d < 0) {
		printf("no real roots\n");
	} else if (a != 0) {
		double r1 = (-b + sqrt(d))/(2*a);
		double r2 = (-b - sqrt(d))/(2*a);

		printf("roots for are %f, %f\n", r1, r2);
	} else if (b != 0) {
		double r1 = -c / b;
		printf("root is %f\n", r1);
	} else {
		if (c != 0) {
			printf("no solutions\n");
		} else {
			printf("many solutions\n");
		}
	}
	printf("\n");
}