/*** özdeğer bulma programı ***/


#include <stdio.h>
#include <math.h>


void Quad3Solve(double a, double b, double c, double d);
int oldmain(double e, double f, double g, double h);


struct df {
	double x1Im, x2Im, x3Im;
	double x1Re, x2Re, x3Re;
};

struct df dataForm;
double PI = 3.14159265;


int oldmain(double e, double f, double g, double h) {
	double a,b,c,d;
	
	
		a=e;
		//if(a==0)
	//		printf("The coefficient of the cube of x is 0.
Please use the utility for a SECOND degree quadratic.
No further action taken.
");

		b=-f;
		c=g;
		d=-h;

		/*do {
		printf("d = ");
		scanf("%lf",&d);
		if(d==0)
			printf("One root is 0.
Now divide through by x and use the utility for a SECOND degree quadratic to solve the resulting equation for the other two roots.
No further action taken.");
	} while(d==0);*/
	Quad3Solve(a,b,c,d);
	printf("X1 = %10.8f + %1.8fj
", dataForm.x1Re, dataForm.x1Im);
	printf("X2 = %10.8f + %1.8fj
", dataForm.x2Re, dataForm.x2Im);
	printf("X3 = %10.8f + %1.8fj
", dataForm.x3Re, dataForm.x3Im);

	return 0;
}

void Quad3Solve(double a, double b, double c, double d)
{

	double discrim, q, r, dum1, s, t, term1, r13;

	b /= a;
	c /= a;
	d /= a;

	q = (3.0*c - (b*b))/9.0;
	r = -(27.0*d) + b*(9.0*c - 2.0*(b*b));
	r /= 54.0;

	discrim = q*q*q + r*r;
	dataForm.x1Im = 0; //The first root is always real.
	term1 = (b/3.0);

	if (discrim > 0) { // one root real, two are complex
	 s = r + sqrt(discrim);
	 s = ((s < 0) ? -pow(-s, (1.0/3.0)) : pow(s, (1.0/3.0)));
	 t = r - sqrt(discrim);
	 t = ((t < 0) ? -pow(-t, (1.0/3.0)) : pow(t, (1.0/3.0)));
	 dataForm.x1Re = -term1 + s + t;
	 term1 += (s + t)/2.0;
	 dataForm.x3Re = dataForm.x2Re = -term1;
	 term1 = sqrt(3.0)*(-t + s)/2;
	 dataForm.x2Im = term1;
	 dataForm.x3Im = -term1;
	 return;
	}						 // End if (discrim > 0)
	
	// The remaining options are all real
	dataForm.x3Im = dataForm.x2Im = 0;
	
	if (discrim == 0){ 			// All roots real, at least two are equal.
	 r13 = ((r < 0) ? -pow(-r,(1.0/3.0)) : pow(r,(1.0/3.0)));
	 dataForm.x1Re = -term1 + 2.0*r13;
	 dataForm.x3Re = dataForm.x2Re = -(r13 + term1);
	 return;
	} // End if (discrim == 0)
	
	// Only option left is that all roots are real and unequal (to get here, q < 0)
	q = -q;
	dum1 = q*q*q;
	dum1 = acos(r/sqrt(dum1));
	r13 = 2.0*sqrt(q);
	dataForm.x1Re = -term1 + r13*cos(dum1/3.0);
	dataForm.x2Re = -term1 + r13*cos((dum1 + 2.0*PI)/3.0);
	dataForm.x3Re = -term1 + r13*cos((dum1 + 4.0*PI)/3.0);
	return;
	
}

main()
{
	double a[3][3];
	double x,y,z,t;
	int i,j;

	printf("matrisinizin elemanlarını sırayla giriniz 

");

	for(i=0;i<3;i++)
	{
		for(j=0;j<3;j++)
		{
			printf("lutfen a[%d][%d] elemanini giriniz 
 ",i+1,j+1);
			scanf("%lf",&a[i][j]);
		}
	}
	
		x=1;
		y= a[0][0] + a[1][1] + a[2][2];
		
		z= a[0][0]*a[1][1] - a[0][1]*a[1][0] +a[0][0]*a[2][2] -a[0][2]*a[2][0] +a[1][1]*a[2][2] +a[1][2]*a[2][1];
		
		t=a[0][0]*( a[1][1]*a[2][2] -a[1][2]*a[2][1] ) - a[0][1]*(a[1][0]*a[2][2] +a[1][2]*a[2][0] ) + a[0][2]*(a[1][0]*a[2][1] +a[1][1]*a[2][0]) ;

		oldmain(x, y, z, t);
		
		return 0;
}