function simplified_f = piao_simplify_conic(a) % Description: simplify the conic funtion to normalized form (简化二次曲线使得成为标准型) % % Input: a 1*6 or 6*1 matrix :(a11, 2*a12, a22, 2*a13, 2*a23, a33) % the coefficients of comic funtion :a11*x.^2 + 2*a12*x*y + a22*y.^2 + 2*a13*x + 2*a23*y +a33 % % Output: normalized comic funtion in symbolic form % % % Method: 采用不变量化简二次曲线 参考《解析几何》（吕林根, 许子道等编 ，高等教育出版社） %