之前在高微學過
a€R^n
D(a;r) is a neighborhood of a, denoted by D
f is defined on D
if f€C^2(D)
and Df(a) = 0, D^2f(a) is positive(negative) definite
then a is local minimum(maximum) of f
可是老師今天上課用到
a€R^n
D(a;r) is a neighborhood of a, denoted by D
f is defined on D
if a is local maximum of f
then Df(a) = 0
and Laplacian of f at a <= 0
n
(就是 Σ f_x_i_x_i(a) <= 0 )
i=1
Df(a) = 0我知道是對的
可是哪來Laplacian of f at a <= 0 完全沒看過@@
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