Re: [python-control-discuss] consistency of parameters to phase_plot()

[Richard M. <mu...@cd...>]

Looks good to me (I think I'm the original author of the phase_plot function).

-richard

On 21 Oct 2012, at 11:22 , Scott C. Livingston <sli...@ca...> wrote:

> The docstring for phase_plot() (in src/phaseplot.py) concerning the parameter "T" is
> 
>  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.
> 
> It appears to me that the second possibility of "list of length len(X0)" is not actually implemented.  Instead, if T is an array, then it is used in the call to odeint() directly.  I propose adding the claimed functionality and further, in the case that T is a list, allowing any element to be an array itself.  A patch achieving this is below.  Existing code that uses phase_plot() would be unaffected by this change assuming that T is never given as a list.
> 
> Index: src/phaseplot.py
> ===================================================================
> --- src/phaseplot.py	(revision 202)
> +++ src/phaseplot.py	(working copy)
> @@ -176,6 +176,8 @@
>     dx = np.empty((nr, Narrows, 2))
> 
>     # See if we were passed a simulation time
> +    if isinstance(T, list) and len(T) != nr:
> +        raise TypeError("Insufficient number of simulation times given for initial conditions.")
>     if (T == None):
>         T = 50
> 
> @@ -197,6 +199,10 @@
> 
>     # Generate the streamlines for each initial condition
>     for i in range(nr):
> +        if isinstance(T, list):
> +            TSPAN = T[i]
> +            if (isinstance(TSPAN, (int, float))):
> +                TSPAN = np.linspace(0, TSPAN, 100);
>         state = odeint(odefun, X0[i], TSPAN, args=parms);
>         time = TSPAN
>         mpl.hold(True);
> 
> 
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