/* Shengjin's Formulas Univariate cubic equation aX ^ 3 + bX ^ 2 + cX + d = 0, (a, b, c, d < R, and a!= 0). Multiple root discriminant: delta1 = b^2-3*a*c; delta2 = b*c-9*a*d; delta3 = c^2-3*b*d, The total discriminant is delta=delta2^2-4*delta1*delta3. When delta1 = delta2 = 0, Shengjin Formula (1): X1=X2=X3=-b/(3*a)=-c/b=-3d/c. When delta=B^2-4*A*C>0, Shengjin Formula II: Y1= delta1*b + 3*a *((-B + (delta)^1/2))/ 2. Y2= delta1*b + 3*a *((-B - (delta)^1/2))/ 2. x1=(-b-Y1^(1/3) - Y1^(1/3)/(3*a); X2=(-2*b+Y1^(1/3)+Y2^(1/3)/(6*a)+3^(1/2)* (Y1^(1/3)-Y2^(1/3)/(6a)i, X3=(-2*b+Y1^(1/3)+Y2^(1/3)/(6*a