A popular method to visualise solutions, to qualitatively predict their behaviour as time t increases, and to get an idea whether a stationary point is stable is the combination of [[Direction Field|direction fields]] with phase portraits. A phase portrait (also called phase diagram) of a [[Autonomous 2 x 2 System of First Order Ordinary Differential Equations]] is a set of curves in the $x_{1}$-$x_{2}$-plane that are parametrised by solutions to this system. These curves traced out by solutions are so-called trajectories. See [[Numerical Solutions of ODEs]].