摘要
用驻点的去心邻域内各点P处函数沿以驻点为端点的过点P的射线方向的方向导数是否同号,来判定二元函数f(x,y)在fxxfyy-f2xy=0时的极限。
The extreme value of binary function at f_(xx)f_(yy)-f^2_(xy)=0 is judged by its direction derivative which follows ray starting from stable point and passing point P at every point P in noncentral neighborhood of stable point.
出处
《辽宁工学院学报》
2004年第3期66-68,共3页
Journal of Liaoning Institute of Technology(Natural Science Edition)
关键词
函数
极值
驻点
去心邻域
方向导数
stable point
noncentral neighborhood
direction derivative
