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Apr 28, 2016 at 17:38 history edited hardmath CC BY-SA 3.0
fix broken link
Jul 7, 2014 at 6:20 vote accept Martin Wang
Jul 7, 2014 at 5:33 vote accept Martin Wang
Jul 7, 2014 at 5:33
Jul 7, 2014 at 3:16 comment added user147263 @MartinWang Okay, I clarified the answer.
Jul 7, 2014 at 3:15 history edited user147263 CC BY-SA 3.0
added 401 characters in body
Jul 7, 2014 at 1:15 comment added Martin Wang Actually, it's called Morse Index. In my understanding, when considering a function $F(X)$, the morse index at critical point is number of negative eigen values of hessian matrix. however, when considering a gradient flow $X'=F(X)$, the morse index is defined as number of positive eigen values.
Jul 7, 2014 at 1:01 comment added Martin Wang It's still the number of negative eigen values of $D^2F(x_0)$. A sink in the sense of vector field is corresponding to the index $2$, which is not literally consistent with the sink concept by intuition.
Jul 6, 2014 at 17:25 comment added user147263 @MartinWang In the question you have two versions of index: the first one gives 0 for a sink, the other gives 2. What is the definitions of the second one?
Jul 6, 2014 at 17:22 comment added Martin Wang Both indices are index of $F$ at critical point $x_0$, i.e. number of negative eigen values of $D^2F(x_0)$. I don't mention the degree/index of a vector field stationary point.
Jul 6, 2014 at 14:43 history answered user147263 CC BY-SA 3.0