# Talk:Phase plane method

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## Merge to phase plane

• "applicable for second order systems only, is a plot with axes being the values of the two state variables, ${\displaystyle x_{2}}$ vs. ${\displaystyle x_{1}}$" <--- What does "order" mean to a reader? Also wrong terminology, "order" in this context would refer to the order of the differential equation (e.x. "2nd order linear differential equation" etc.), not to the number of variables. Furthermore an n-order diff eqn can always be reduced to a system of n coupled 1st order eqns. So the terminology used is misleading.
• "Vectors representing the derivatives ${\displaystyle [f_{2}(x_{1},x_{2}),f_{1}(x_{1},x_{2})]}$ at representative points are drawn." <-- Would be nice to explicitly state that these are derivatives using derivative notation.