control.phase_plot

control.phase_plot(odefun, X=None, Y=None, scale=1, X0=None, T=None, lingrid=None, lintime=None, logtime=None, timepts=None, parms=(), verbose=True)

Phase plot for 2D dynamical systems

Produces a vector field or stream line plot for a planar system.

Call signatures:
phase_plot(func, X, Y, …) - display vector field on meshgrid phase_plot(func, X, Y, scale, …) - scale arrows phase_plot(func. X0=(…), T=Tmax, …) - display stream lines phase_plot(func, X, Y, X0=[…], T=Tmax, …) - plot both phase_plot(func, X0=[…], T=Tmax, lingrid=N, …) - plot both phase_plot(func, X0=[…], lintime=N, …) - stream lines with arrows
Parameters:
  • func (callable(x, t, ..)) – Computes the time derivative of y (compatible with odeint). The function should be the same for as used for scipy.integrate. Namely, it should be a function of the form dxdt = F(x, t) that accepts a state x of dimension 2 and returns a derivative dx/dt of dimension 2.
  • Y (X,) – Two 3-element sequences specifying x and y coordinates of a grid. These arguments are passed to linspace and meshgrid to generate the points at which the vector field is plotted. If absent (or None), the vector field is not plotted.
  • scale (float, optional) – Scale size of arrows; default = 1
  • X0 (ndarray of initial conditions, optional) – List of initial conditions from which streamlines are plotted. Each initial condition should be a pair of numbers.
  • T (array-like or number, optional) – Length of time to run simulations that generate streamlines. If a single number, the same simulation time is used for all initial conditions. Otherwise, should be a list of length len(X0) that gives the simulation time for each initial condition. Default value = 50.
  • lingrid (integer or 2-tuple of integers, optional) – Argument is either N or (N, M). If X0 is given and X, Y are missing, a grid of arrows is produced using the limits of the initial conditions, with N grid points in each dimension or N grid points in x and M grid points in y.
  • lintime (integer or tuple (integer, float), optional) – If a single integer N is given, draw N arrows using equally space time points. If a tuple (N, lambda) is given, draw N arrows using exponential time constant lambda
  • timepts (array-like, optional) – Draw arrows at the given list times [t1, t2, …]
  • parms (tuple, optional) – List of parameters to pass to vector field: func(x, t, *parms)

See also

box_grid()
construct box-shaped grid of initial conditions

Examples