A fixed point for which the stability matrix has both eigenvalues of the same sign (i.e.,
both are positive or both are negative).
If 
,
then the node is called stable; if 
, then the node is called an unstable
node.
Fixed Point Node
See also
Stable Node, Unstable NodeExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Fixed Point Node." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/FixedPointNode.html