code:

 a = pow(raydir[0],4) + pow(raydir[1],4) + pow(raydir[2],4) + 
		2.0* raydir[0]*raydir[0]*raydir[1]*raydir[1] + 
		2.0* raydir[0]*raydir[0]*raydir[2]*raydir[2] + 
		2.0* raydir[1]*raydir[1]*raydir[2]*raydir[2];

	b = 4.0*pow(raydir[0],3)*raypos[0] + 4.0*pow(raydir[1],3)*raypos[1] + 4.0*pow(raydir[2],3)*raypos[2] +
        4.0*raydir[0]*raydir[0]*raydir[1]*raypos[1] + 4.0*raydir[0]*raydir[0]*raydir[2]*raypos[2] +
		4.0*raydir[1]*raydir[1]*raydir[0]*raypos[0] + 4.0*raydir[1]*raydir[1]*raydir[2]*raypos[2] +
		4.0*raydir[2]*raydir[2]*raydir[0]*raypos[0] + 4.0*raydir[2]*raydir[2]*raydir[1]*raypos[1];

	c = -2.0*majorradius*majorradius*raydir[0]*raydir[0] - 2.0*majorradius*majorradius*raydir[1]*raydir[1] -
		 2.0*majorradius*majorradius*raydir[2]*raydir[2] - 2.0*minorradius*minorradius*raydir[0]*raydir[0] -
		 2.0*minorradius*minorradius*raydir[1]*raydir[1] - 2.0*minorradius*minorradius*raydir[2]*raydir[2] +
		 6.0*raydir[0]*raydir[0]*raypos[0]*raypos[0] + 2.0*raypos[0]*raypos[0]*raydir[1]*raydir[1] +
		 8.0*raydir[0]*raypos[0]*raydir[1]*raypos[1] + 2.0*raypos[1]*raypos[1]*raydir[0]*raydir[0] +
		 6.0*raydir[1]*raydir[1]*raypos[1]*raypos[1] + 2.0*raypos[0]*raypos[0]*raydir[2]*raydir[2] +
		 2.0*raypos[1]*raypos[1]*raydir[2]*raydir[2] + 8.0*raydir[0]*raypos[0]*raydir[2]*raypos[2] +
		 8.0*raydir[1]*raypos[1]*raydir[2]*raypos[2] + + 2.0*raypos[2]*raypos[2]*raydir[1]*raydir[1] +
		 6.0*raydir[2]*raydir[2]*raypos[2]*raypos[2];
	
	d = -4.0*majorradius*majorradius*raydir[0]*raypos[0] - 4.0*majorradius*majorradius*raydir[1]*raypos[1] + 
		 4.0*majorradius*majorradius*raydir[2]*raypos[2] - 4.0*minorradius*minorradius*raydir[0]*raypos[0] -
		 4.0*minorradius*minorradius*raydir[1]*raypos[1] - 4.0*minorradius*minorradius*raydir[2]*raypos[2] +
		 4.0*raydir[0]*pow(raypos[0],3) + 4.0*raypos[0]*raypos[0]*raydir[1]*raypos[1] +
		 4.0*raypos[1]*raypos[1]*raydir[0]*raypos[0] + 4.0*raydir[1]*pow(raypos[1],3) + 
		 4.0*raypos[0]*raypos[0]*raydir[2]*raypos[2] + 4.0*raypos[1]*raypos[1]*raydir[2]*raypos[2] +
		 4.0*raypos[2]*raypos[2]*raydir[0]*raypos[0] + 4.0*raypos[2]*raypos[2]*raydir[1]*raypos[1] + 
		 4.0*raydir[2]*pow(raypos[2],3);
    
	e = pow(majorradius,4) - 2.0*majorradius*majorradius*raypos[0]*raypos[0] -
		2.0*majorradius*majorradius*raypos[1]*raypos[1] + 2.0*majorradius*majorradius*raypos[2]*raypos[2] + 
		pow(minorradius,4) - 2.0*minorradius*minorradius*majorradius*majorradius - 
		2.0*minorradius*minorradius*raypos[0]*raypos[0] - 2.0*minorradius*minorradius*raypos[1]*raypos[1] -
		2.0*minorradius*minorradius*raypos[2]*raypos[2] + pow(raypos[0],4) + pow(raypos[1],4) + 
		pow(raypos[2],4) + 2.0*raypos[0]*raypos[0]*raypos[1]*raypos[1] +
		2.0*raypos[0]*raypos[0]*raypos[2]*raypos[2] + 2.0*raypos[2]*raypos[2]*raypos[1]*raypos[1];
	
	
	term1 = pow(2,1/3)*(c*c-3*b*d+12*a*e);

	term2 = sqrt(pow((2.0*c*c*c - 9.0*b*d*c - 72.0*a*e*c + 27.0*a*d*d + 27.0*b*b*e),2) -
		    4.0*pow((c*c - 3.0*b*d + 12.0*a*e),3));

	term3 = pow((2.0*c*c*c - 9.0*b*d*c - 72.0*a*e*c +27.0*a*d*d + term2 + 27.0*b*b*e),1/3);
	
	term4 = term3/(3*pow(2,1/3)*a);
			
	term5 = term1/(3*a*term3); 
		
    
	t1 = (-b)/(4*a) - 0.5*sqrt((b*b)/(4*a*a) - (2*c)/(3*a) + term4 + term5) -
		0.5*(sqrt((b*b)/(2*a*a) - (4*c)/(3*a) - term4 - term5 -
		((-b*b*b)/(a*a*a) + (4*c*b)/(a*a) -(8*d)/a) /
		4*sqrt((b*b)/(4*a*a) -(2*c)/(3*a) + term4 + term5)));
	
	t2 = (-b)/(4*a) - 0.5*sqrt((b*b)/(4*a*a) - (2*c)/(3*a) + term4 + term5) +
		0.5*(sqrt((b*b)/(2*a*a) - (4*c)/(3*a) - term4 - term5 -
		((-b*b*b)/(a*a*a) + (4*c*b)/(a*a) -(8*d)/a) /
		4*sqrt((b*b)/(4*a*a) -(2*c)/(3*a) + term4 + term5)));
	
	t3 = (-b)/(4*a) + 0.5*sqrt((b*b)/(4*a*a) - (2*c)/(3*a) + term4 + term5) -
		0.5*(sqrt((b*b)/(2*a*a) - (4*c)/(3*a) - term4 - term5 +
		((-b*b*b)/(a*a*a) + (4*c*b)/(a*a) -(8*d)/a) /
		4*sqrt((b*b)/(4*a*a) -(2*c)/(3*a) + term4 + term5)));
		
		
	t4 = (-b)/(4*a) + 0.5*sqrt((b*b)/(4*a*a) - (2*c)/(3*a) + term4 + term5) +
		0.5*(sqrt((b*b)/(2*a*a) - (4*c)/(3*a) - term4 - term5 +
		((-b*b*b)/(a*a*a) + (4*c*b)/(a*a) -(8*d)/a) /
		4*sqrt((b*b)/(4*a*a) -(2*c)/(3*a) + term4 + term5)));

Ora posso andare al concerto dei Meshuggah...


P.S. : Alf, c'hai la casella dei PM piena!!!